
Class _iJlA3^ 

Book ^^V:^_ 

GopyrightN? 



COPYRIGHT DEPOSn; 



^ 



THE ENGINEERING RECORD SERIES 



STEAM POWER PLANTS 



THEIR 



DESIGN AND CONSTRUCTION 



BY 

HENRY C MEYER. Jr.. M. E. 



SECOND EDITION, CORRECTED 



NEW YORK 

McGRAW PUBLISHING CO. 

114 Liberty Street 

1905 



LIBRARY of CONGRESS 
Two Cooies Recefved 

APR 13 1906 

^ Copyriarm Entry 
OiAssn XXc. No. 



Copyrighted, 190S, by The Enoineering Record, 
and, 1905, by the McGraw Publishing Company, New York. 

Beprinted by the McGraw Pubushing Company, May, 1903, August, 1904. 
Second edition, corrected, printed, June, 1905. 



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INTRODUCTORY NOTE, 



Frequently engineers and others in charge of a manufac-^ 
turing business, be it a mill, factory or electric generating- 
station, are called upon to design and purchase a steam power 
plant or parts of it when their knowledge of the machinery 
that goes into such a plant is more or less limited, and without- 
being able to obtain the benefit of the advice of a competent: 
consulting engineer. It is hoped that this book will be of 
special value to this class and of some value to all ia- 
terested in steam power plant construction. Part of the text 
appeared in a series of articles in The Engineering 
Record and when the demand for them seemed to warrant 
their being published in book form they were thoroughly re- 
vised and considerable new matter added. A number of the 
illustrations have been selected from articles printed in The 
Engineering Record during the last two or three years de- 
scriptive of steam power plant construction. They are re- 
printed without the text that accompanied them, thinking 
they would be suggestive. 



CONTENTS. 



CHAPTER 1.— Design of Steam Power Plants. 

Location of Plant — Drawings — Type of Power House — Building — Foundations 
— Engine Foundations. 

CHAPTER II. — Proportioning Steam Boilers. 

Heating Surface Necessary — Boiler Horse Power — Types of Boilers — Division 
of Heating Surface in Units — Importance of Proper Grate Surfaces — Propor- 
tioning Grate — Coal — Semi-Bituminous Coals — Bituminous Coal — Anthracite Coal. 

CHAPTER III.— Design of Tubular Boilers and Boiler Specifications. 

Thickness of Shell — Braces — Supporting Boilers — Tubes — Riveting — Boiler Set- 
tings — Boiler Specifications — Smoke Flues — Water Tube Boiler Specifications. 

CHAPTER IV.— Selection of Engines. 

Selection of Type — Steam Pressure^ — Rotative Speed — Piston Speed — Mean Effec- 
tive Pressures — Proportioning Cylinders for Simple Corliss Engines — Simple 
High vSpeed Engines — Simple Medium Speed Engines — Proportioning Cylinders 
for Compound Engines — Mean Effective Pressures for Compound Engines — - 
Variable Loads and Overload Capacities — Superheated Steam, Steam Jackets 
and Reheaters — Steam Turbines. 

CHAPTER v.— Specifications for Steam Engines. 

CHAPTER VI.— Steam and Water Piping. 

Drawings — -Principles Involved — Exhaust Piping for Condensing Plants — Piping 
Between Cylinders of Compound Engines — Exhaust Piping for Non-Condensing 
Plants — Care of Drips — Feed Water Piping — Kind of Pipe — Size of Steam Pipes 
— Size of Exhaust Pipes — Kind of Fittings — Covering Pipes — Specifications for 
Piping. 

CHAPTER VII.— Condensers. 

Saving Due to Condensers — Types of Condensers — Location — Water Necessary 

for Condensing— Sources of Water Supply — Cooling Towers — Proportioning 
Condensers — Specifications. 

CHAPTER VIII.— Feed Water Heaters and Economizers. 

Types of Heaters — Uses for Heaters — Condensation in Heaters — Purchasing 
Heaters — Economizers. 

CHAPTER IX.— Mechanical Draft. 

Theory of Combustion — Need of Ample Draft — Advantages of Mechanical Draft 
— Theory of Fans — Design of Fans. 

CHAPTER X.— Chimneys. 

Size of Chimneys — Capacity — Thickness of Walls — Linings — Materials — Masonry 
Chimney Foundations — Steel Chimneys — Foundations for Self-Supporting Steel 
Chimneys. 

CHAPTER XL — Coal Handling, Water Supply and Purification. 

Coal Handling Machinery — Cost of Coal Handling — Cost of Boiler Room Labor 
— Mechanical Stokers — Pulverized Fuel — Supply of Boiler Water — Water Soft- 
ening — Purifying with Exhaust Steam — Purifying by Live Steam — Purifying by- 
Chemical Treatment. 



Chapter I. — The Design of Steam Power Plants. 



No better service can be done the non-expert about to construct 
a steam plant than to advise him to engage at the outset of the 
project some capable engineer to design the plant and superintend 
its installation. In spite of the advantages of having work 
planned and carried out by such men; it will always be, probably, 
that a very considerable proportion of the work done will be con- 
structed for one reason or another, by persons with a semi-tech- 
nical training without the aid of the expert engineer. It is, 
therefore, proposed to give data and information which, it is 
hoped, will aid the engineer who cannot be called an expert in 
selecting the various kinds of machinery and apparatus that make 
up a steam power plant, to discuss specifications for these in a 
general way, and, in some instances, to outline the manner in 
which they should be purchased. 

It is the practice of many engineers in steam-plant construction 
to invite bids on apparatus described very generally in a specifica- 
tion and intended to perform a service under conditions that are 
named, the idea of the engineer being to allow each bidder to pro- 
portion the parts of the apparatus he is to furnish and to quote 
a price on it. When bids are received under these conditions, it 
generally follows that there is a variation in the size of the ma- 
chinery offered by different makers to do the same work, and the 
lowest in price may not be best adapted for the conditions. An 
engine, boiler or pump, in fact almost everything about a steam 
plant, may do the work required of it, but it may be so propor- 
tioned as to do it in a manner that is not best for the owner. For 
instance, while an engine may give the required power, its cylin- 
ders may be so small that it requires an excessively large amount 
of steam to run it, or a boiler may be so small that an abnormal 
amount of coal must be burned in order to generate the steam 
required. The expert engineer is, of course, able to detect and 
reject bids on deficient apparatus, yet when the size of the ap- 
paratus is fixed by the contractor it may happen that the pur- 



2 STEAM POWER PLANTS. 

chaser, who is not an expert, will accept machinery which is not 
best adapted for the service that it is to perform, particularly if 
the too frequent custom of purchasing the apparatus lowest in 
price is followed. 

There are other methods of buying apparatus for a steam plant. 
One is to go to a reputable manufacturer or contracting engineer 
and engage him to build the machinery wanted and pay what is 
asked for it. Such a contractor should not, however, be placed 
in competition with others if he is to design a plant to fill the re- 
quirements of the owner, for if this is done the contractor's in- 
terest is to design a cheaper plant than will be proposed by his 
competitor, whose bid is based on the plant designed by him, and 
this kind of competition sometimes results in inferior apparatus 
being supplied. 

Another method of purchasing is to have the engineer state in 
his specification the dimensions of the apparatus wanted, permit- 
ting, however, a departure from these specified dimensions in 
order that a manufacturer can make use of his standard patterns, 
provided such a course is not detrimental to the purchaser's in- 
terest. When all manufacturers bid on the same basis their bids 
are lower and the purchaser is sure of getting a properly-propor- 
tioned machine, provided the engineer who prepares the plans 
and specifications is capable. Many believe the last two methods 
of procedure much preferable to the first. Latitude given an im- 
prudent contractor, in the way of fixing the dimensions of the 
apparatus he is to supply, may, in a measure, be covered by de- 
manding a guarantee as to efficiency, yet tests necessary to de- 
termine if the guarantees are fulfilled are expensive and are there- 
fore generally omitted. 

Location of Plant. — One of the first questions to be decided in 
the construction of a power plant is its location. This depends 
on several factors, the most important of which are, the ease with 
which the power may be transmitted from the generating source 
to the locations of the demand, the cost of delivering coal and 
removing ashes from the power house, and the availability of a 
supply of water for condensing purposes. 

The first factor, the ease with which power may be transmitted 
from the generating source to the machines utilizing it, is the one 
that frequently decides whether an electric or belt and shafting 
system of transmission is to be used. It is, of course, impossible 



STEAM POWER PLANTS. 3 

to give any general rule applicable to all cases, as each situation 
demands a thorough investigation of the cost of installing and 
operating both plants. In arriving at their relative costs of opera- 
tion, the interest on the investments, the repairs, the fuel cost, the 
cost of attendance, supplies, etc., have to be reckoned. Generally 
speaking, it may be said that in any situation where the load on 
the power plant is practically constant throughout the working 
day, as in a textile mill, and where the power house may be lo- 
cated close to the lines of shafting so that belts may be carried 
from the engine to the shafting without the use of gearing, 
quarter-turn belts, etc., the belt and shafting system of transmis- 
sion seems the most favored. If, however, the manufacturing 
establishment consists of a number of separate buildings in which 
lines of shafting are at different angles, so as to require several 
separate power plants or else a complicated system of belts or 
gears, the electric system possesses advantages as regards cost of 
operation that makes its adoption advisable. Again, the tendency 
in establishments where the work is similar to that of a large ma- 
chine or bridge shop, where the tools are used intermittently, 
where one or two departments may run overtime, the electric sys- 
tem is rapidly gaining friends. The reason for this is not the 
difference in the operating expenses, which are slight, inasmuch 
as a machine shop requires a very small amount of power for its 
operation, but in the greater convenience and cleanliness of the 
electric system. One solution of the problem of transmitting 
power when shafts lie in directions that are not parallel is the rope 
drive. This has been used with the greatest success in many 
plants. Its low first cost and cost of repairs and the flexibility of 
the system make it well worth considering in many installations. 
The cost of handling coal and removing ashes in a power house 
may be a considerable item in the operating expenses, and large 
plants are therefore usually equipped with coal-handling ma- 
chinery. Some steam plants are so arranged that railway cars or 
coal cars may be run over a receiving hopper from which the coal 
is conveyed mechanically to storage bunkers over the boilers and 
chuted from the bunkers to the furnaces by gravity. If a plant is 
not to be provided with coal-handling machinery, it is well, if 
convenient, to provide a trestle so that cars may be run over and 
dump into a bunker opposite the furnace doors in order that the 
coal may fall by gravity through holes in the wall separating the 



4 STEAM POWER PLANTS. 

bunker from the boiler room, on to the floor of the latter, in front 
of the furnace doors. 

The value of water in sufficient quantity to condense the steam 
exhausted by the engines often determines the location of the 
power house. From 15 to 20 per cent, of the fuel used by a non- 
condensing engine will be saved if it is operated with a condenser. 
Each pound of steam exhausted by an engine requires a supply of 
30 to 35 pounds of water for the condenser, so it will be seen that 
the water needed for condensing purposes is often a considerable 
quantity. Sometimes when a power house cannot be located on 
the bank of a stream from which a supply for this purpose is 
available, a pipe or conduit can be laid from a river to a well near 
the power house, the grade of the conduit being below that of 
minimum low water. The injection pipe, as the pipe that conveys 
the water to the condenser is called, can then be run from this 
well to the condenser, which is usually located close to the engine. 
Because of the vacuum in the condenser, the water will rise in the 
injection pipe from a lower level to the condenser. It is not ad- 
visable, however, to attempt to lift the injection water over 20 
feet. Where the lift would be slightly greater than this the con- 
denser can be placed in a pit. Since the development of the cool- 
ing tower, an apparatus for cooling condensing water so that it 
can be used over and over again, condensing plants are not so de- 
pendent on an abundant water supply, as they were before this 
apparatus was perfected, hence the importance of locating 
a plant by a stream for condensing purposes is not as great as it 
was once. 

Drawings. — Complete and accurate drawings of all of the de- 
tails of a steam plant are a necessity. It is well to make assembled 
drawings showing the plant in plan and as many elevations as may 
be necessary to make the arrangement perfectly clear. Assembled 
drawings insure all parts of the plant fitting together properly, 
and prevent mistakes such as attempting to run steam pipes where 
a building column ought to be, and so on. If assembled drawings 
are to be made, the scale assumed should be sufficiently large to 
show the steam-pipe system. Three-eighths of an inch to the foot 
is about as small as can well be used. As soon as contracts are 
made for engine, boilers, feed-water heaters, pumps, etc., accu- 
rately dimensioned blue-prints showing the machinery in plan and 
elevation should be obtained from the contractors. Experience 




UJJ 



Plate i.— Lincoln Whakf Power Station, Boston Elevated Railway Co. 
george a. kimball, chief engineer; sheaff & jaastkd. consulting engineers. 



STEAM POWER PLANTS. 5 

has shown that it is well, with some firms at least, in order to 
avoid delay, to get these blue-prints before the contracts are let. 
Contracts for the building, steel work, etc., should not be made 
until the machinery is contracted for, since it may not be possible 
to obtain the machinery which was contemplated at the time the 
building plans were made, and machinery then available may not 
fit. It is, of course, essential that the building be fitted to the ma- 
chinery, not the machinery fitted to the building. 

Type of Power House. — Generally the relative location of the 
engine and boiler rooms is determined by some local condition. 
Where it can be done, however, it is better to locate the engine 
and boilers in one building, with a wall between them, and to place 
them in parallel rows with the cylinders of the engine adjacent 
to the rear of the boilers. This is- particularly the best arrange- 
ment if the plant is likely to be enlarged in the future. The steam 
pipe connecting the boiler and engine or engines is the most di- 
rect in this arrangement, and it can be most readily enlarged. If 
the engine and boiler houses are placed end to end and contain two 
or more boilers supplying one engine, the proper size of piping 
for such a plant will be inadequate if another engine is added at 
one end of the plant and more boilers installed at the other. 

Where land is very expensive, boilers are sometimes placed in 
buildings on two or more floors. Ordinarily, however, the 
boiler-room floor is usually on the level with the outside ground, 
while the engine-room floor with large engines is invariably 
higher, usually from 6 to 12 feet or more, depending on the height 
of the engine foundations. Sometimes an engine is installed 
where the engine-room floor is on the ground level. When this 
is done, it is necessary to construct a pit for the condenser, if such 
an auxiliary is used, also pipe trenches and, if the engine is a large 
one, a pit for the fly-wheel. It perhaps ought to be stated at this 
time that a condenser ought always to be below the engine, as the 
pipe leading to the condenser cannot rise at any point without in- 
troducing a dangerous element into the power plant. The arrange- 
ment that necessitates the construction of pits ought to be avoided, 
if it is possible, as it is difficult to construct a water-tight pit for 
the fly-wheel and condenser, because the vibration of the engine is 
apt to crack the lining of the pit and allow water to enter, if there 
is any in the soil. The trenches for the exhaust piping have to be 
covered and the piping is not nearly so accessible when in a cov- 



G STEAM POWER PLANTS. 

ered trench as it is when in the basement usually provided under 
engine rooms. 

Building. — A building for a power house should, if possible, 
be constructed of fireproof materials. Brick walls with steel 
trusses supporting a wooden roof covered with tar and gravel, or 
with some form of fireproof construction, is the usual construc- 
tion. The brick walls sometimes carry the roof trusses and tracks 
for traveling cranes, and again these are supported by steel col- 
umns resting on the foundations and imbedded in the brick walls, 
the latter, however, carrying only their own weight. The build- 
ing should be designed by an architect or structural engineer. The 
construction of the building can be done by bridge shops making 
a specialty of constructing buildings of this character and supply- 
ing the steelwork for them. 

■ The buildings should.be of such a size that the machinery in 
them is not cramped. When there are several machines in an 
engine room it should be remembered when locating them that it 
is sometimes necessary to stop a machine very quickly. It is well, 
therefore, to place all machinery in such a position that it is read- 
ily accessible to the man or men in charge of it. Provision should 
be made in planning and constructing a power house for bring- 
ing the machinery into the building after it is erected, and a door 
of sufficient size to admit the largest part of a machine must be 
provided. Ample room must be left around the horizontal steam 
and water cylinders to be able to remove piston rods if it should 
be necessary, without removing the cylinder from its foundations. 
Enough space must be left between the foundations of adjacent 
engines and between foundations and engine-room walls to allow 
a man to get between them to reach the foundation bolts. In a 
boiler room, there must be a clear space in front of the boilers 
at least as wide as the boiler tubes are long. The distance between 
the rear of the boilers and the wall need not be greater than five 
or six feet, or enough to allow a wheelbarrow to be placed oppo- 
site the soot door in the rear of the boiler setting, if such a door is 
provided. 

Foundations. — The character of the soil underlying the site for 
a power house should be carefully examined in order that the 
foundations can be so planned as to keep the load imposed by the 
buildings and machinery within the safe limit. For ordinary one- 
story buildings where the loads are not excessive, holes should be 



STEAM POWER PLANTS. 




Plan. 



Figure 1. — Ei'ctric Power Station, Designed by Dean & Main. 



8 



STEAM POWER PLANTS. 



dug at numerous points over the site and the character of the soil 
determined. As the magnitude of the work increases more care 
should be taken. In important work a competent specialist in 




riG.2 



The Eboineeriug RECORa 



Figure 2. — Piping in Power House ;Lockwood, Greene & Co. 
Engineers. 



foundation work should be consulted. As to the bearing capacity 
of different soils, the New York Building Code states : ''Different 
soils, excluding mud, at the bottom of the footings shall be 



STEAM POWER PLANTS. 9 

deemed to safely sustain the following loads to the superficial 
foot, namely: Soft clay, one ton per square foot; ordinary clay 
and sand together, in layers, wet and springy, two tons per square 
foot ; loam, clay or fine sand, firm and dry, three tons per square 
foot; very firm, coarse sand, stiff gravel or hard clay, four tons 
per square foot." 




Figure 3. — Section Main Steam Piping, Lincoln Wharf Station. 



If loose rock is found it should be removed, solid rock should 
be dressed off in steps with vertical risers and horizontal treads 
so that the pressure will be exerted everywhere in a vertical di- 
rection. Solid rock will stand almost any load that can be im- 
posed upon it. If soil of low bearing power is found, piling is 
usually resorted to. Piles may be of spruce or hemlock at least 5 



10 STEAM POWER PLANTS. 

inches in diameter at the point and lo inches in diameter at the 
butt for piles 20 feet or less in length, and 6 inches at the point 
and 12 inches at the butt for piles over 20 feet in length. The 
bearing power of piles not driven to rock or hardpan or similar 
firm material may be calculated by the Wellington formula, in 
which the safe bearing power in tons is equal to twice the weight 
of the hammer in tons multiplied by the height of the fall in feet 
divided by one plus the penetration of pile under the last blow 
in inches. From a knowledge of the total load to be carried and 
the load that each pile will support, the number of piles necessary 
under a weight to be supported can be calculated. If the soil is 
not firm, the bearing power of a pile should be taken much less 
than that given by the formula, in order to allow for decrease in 
strength due to vibrations of the machinery. To avoid decay the 
piles should be cut off at the level of the ground water or not 
more than one foot above it. 

It is getting to be the practice in power-house construction 
where piles are used, to saw off the heads of the piles to a uniform 
grade, then excavate the materials between the heads of the piles 
for a depth of a foot or so and lay a bed of concrete sometimes 
several feet in thickness between the heads of the piles and over 
their tops. An 8-foot bed of concrete over piles on 30-inch cen- 
ters was used as a foundation for the 96th Street power house of 
the Metropolitan Street Railway Company in New York City. 
If the soil underlying a power house site is found to possess too 
low a bearing power for the foundations of the engines and boil- 
ers to be constructed directly on it, concrete beds may be laid so 
as to distribute the load. Sometimes a concrete bed is laid under 
the engine foundations and another under the boilers. Again 
the entire site is covered with a bed of concrete and the wall foot- 
ings and machinery foundations built directly upon it. 

Engine Foundations. — These are almost invariably constructed 
by the owner, the engine builder furnishing the drawings. The 
latter generally consist of accurately dimensioned drawings show- 
ing the foundations in plan and one or two elevations and also 
a drawing of a board template which has to be made for locating 
the foundation bolts. A hole is bored in the template where each 
bolt is located, and the template is supported over the place where 
the foundation is to be constructed, at such a height that the foun- 
dation bolts may be suspended in the position that they will finally 



STEAM POWER PLANTS. 11 

occupy, by passing them through the holes in the template, the nut 
on the upper end holding them in position. The foundation is 
then built around the bolts, leaving holes about them an inch or 
two greater in diameter than the bolts themselves, so that the lat- 
ter may be moved slightly, to pass through the holes in the en- 
gine bed plate, should an error occur in locating the position of 
the bolts or the holes in the engine bed. 

Foundations for engines are sometimes constructed on a very 
thick bed of concrete, as has been explained. This is not always 
necessary, and where good loam and clay are known to exist for 
some distance below the surface of the ground, the earth may be 
leveled off and the foundation commenced on a layer of concrete 
just thick enough to give a good bearing. If loose rock or poor 
earth is found, this should be removed and the excavation filled 
with concrete, in which loose stones, old bricks, etc., may be im- 
bedded, care being taken to put them in layers alternating with 
tRe concrete, which should be so placed and rammed as to make 
sure that there are no voids. This should be continued up to the 
level at which the regular brick or concrete foundations are to 
commence. There seems to be no good reason for using a pure 
concrete bed if the earth is of good quality and the load imposed 
upon it not excessive. Engine foundations should be of brick 
laid in cement mortar made of one part Portland cement to two 
parts clean sharp sand or of concrete. Good concrete is obtained 
by mixing one part good Portland cement, two parts sand and 
four parts broken stone, the latter small enough to pass through a 
2-inch ring. Concrete should be laid in layers not over 6 inches 
thick, each layer being thoroughly rammed before the one above 
is put down. Such a foundation has to be surrounded with board 
walls or forms to suitably hold the concrete while it is being laid. 
A Portland cement concrete foundation ought to stand at least 
two months, and one of brick in Portland cement one month be- 
fore it is loaded, whenever possible to spare the time, but if suit- 
ably proportioned and carefully watched it can be safely loaded 
much sooner, especially if the concrete is made as dry as possible. 



Chapter II. — Proportioning Steam Boilers. 

Heating Surface Necessary. — The function of a steam boiler 
is to transmit to the water it contains as much of the heat gene- 
rated by the combustion of fuel as possible. Each square foot 
of heating surface in the boiler can transmit only a certain 
amount of heat when the highest economy is being realized. By 
increasing the supply of heat a greater amount is transmitted 
and consequently a greater amount of water is evaporated 
by each square foot of heating surface, but with the in- 
crease, the same percentage of the heat generated is not utilized. 
The reason is that after a certain rate of evaporation is reached, 
the maximum capacity of the metal in the boiler plates to trans- 
mit the heat is more nearly reached, and, hence, a larger percen- 
tage of the heat of the fuel passes up the chimney. In other 
words, it is possible to evaporate a certain amount, say three 
pounds, of water per square foot of heating surface in a given 
time and to utilize a certain percentage, say 80 per cent., of the 
heat in the fuel, 20 per cent, going to waste. It is also possible 
to burn more coal and evaporate say five pounds of water per 
square foot of heating surface in the same time, but when doing 
so a greater percentage, perhaps 30 per cent., of the heat of the 
fuel is lost. The selection of the proper amount of heating sur- 
face for a steam boiler is, therefore, a very important matter. 

The best efficiency, under ordinary working conditions, with 
most boilers, is obtained when evaporating about 3 pounds of 
water per square foot of heating surface per hour, from a feed 
temperature of 212 degrees Fahrenheit into steam at atmospheric 
pressure. This is equivalent to allowing nearly 12 square feet 
of heating surface per boiler horse-power. Some water-tube boil- 
ers with certain coals seem to give a good result when the heating 
surface per horse-power is a little less than that stated. Most 
boilers, sometimes, and quite frequently in fact, attain a high effi- 
ciency when the rate of evaporation is considerably higher than 
that given. Such high results with most boilers are usually at- 



STEAM POWER PLANTS. 13 

tained, however, when all of the many conditions affecting- the 
efficiency are such as to produce a good result. Many of these 
conditions are not so favorable when a boiler is operated in or- 
dinary service. For instance, if the boiler surfaces are not clean, 
owing perhaps to the accumulation of scale or soot, the efficiency 
of the heating surface will be more or less impaired. For this 
and other reasons, the writer believes it is well to provide ample 
heating surface for the work to be done, for not only will such 
a course result in a saving of fuel at ordinary rates of evapora- 
tion, but it will make it possible to run a boiler considerably above 
its rating and still maintain a fair efficiency. 

Value of a Boiler Horse-Power. — According to the American 
Society of Mechanical Engineers' standard, a boiler to develop 
one horse-power must raise 30 pounds of water from a tempera- 
ture of 100 degrees Fahrenheit to the temperature of steam at 70 
pounds pressure, and evaporate it into steam at the pressure. This 
is equivalent to evaporating 34^ pounds of water at a tempera- 
ture of 212 degrees into steam^ at atmospheric pressure or ''from 
and at 212 degrees" as it is sometimes called. The term horse- 
power is frequently used when estimating the capacity of steam 
boilers, and the custom of buyers was formerly to ask for boil- 
ers of a certain horse-power. This is an improper way to buy 
boilers unless the amount of heating surface per horse-power is 
closely examined. If bids are called for boilers of a given horse- 
power one bidder might offer a boiler with ample heating surface, 
while another might offer a boiler with much less. Both might 
develop the required horse-power, but the one with deficient heat- 
ing surface might do it only at an increased cost for fuel, as ex- 
plained in a previous paragraph. In saying this it should be borne 
in mind that the efficiency of various classes of surfaces varies 
according to their location and arrangement, but this variation 
in first-class boilers is. confined to narrow limits which can only 
be detected by the expert. 

Advantages of Types of Boilers. — Barrus, in his excellent work 
on "Boiler Tests," states ''that the economy with which different 
types of boilers operate depends more upon their proportions and 
the conditions under which they work, than upon their types ; and, 
moreover, that when these proportions are suitably carried out 
and when the conditions are favorable, the different types of boil- 
ers give substantially the same result." So much for the side of 



14 



STEAM POWER PLANTS. 



efficiency. As to safety, the water-tube boiler is, of course, far 
superior to boilers of the fire-tube type. In fact, water-tube boil- 
ers seldom explode, although the tubes sometimes burst and in- 
jure those firing them. Water-tube boilers also possess an ad- 
vantage in that they contain less water than the shell type, as 
usually designed, and consequently steam can be raised in them 
more quickly. More water can probably be evaporated per square 
foot of heating surface in a water-tube boiler than in one having 
fire tubes, on account of a larger passage for the gases, and pos- 



f^ 


r 


) 








: li"xL"lron. / 










— 2'o" ->l 


M- 




^""/ron.- 



l"P/pe/ 




iiiiirniiir 



I 4" Channel. 



. ■.ti"/i"lron. 



^\ 



4" Channel/' 



Boiler Room Floor. 



: tmntiKxa Recoup. 



Figure 4. — Iron Walk Over Boilers, Designed by Sheaff & Jaasted. 



sibly on account of a better circulation of water in contact with 
the heating surfaces. The efficiency of the two types is about the 
same, the difference depending more upon the proportions and 
management, as Mr. Barrus states, than upon the types. Water- 
tube boilers have increased in favor very rapidly in the past few 
years, particularly for electric work, where large amounts of 
steam are wanted suddenly, and som.etimes without previous 
warning. In spite of the fact that the water-tube boiler pos- 



STEAM POWER PLANTS. 15 

sesses advantages over it, the fire-tube boiler, particularly the 
horizontal return tubular boiler, is still used to a very consider- 
able extent on account of its lov^er cost. An internally-fired 
boiler, such as the Manning, locomotive, Gallov^^ay or Lancashire 
boiler, all of which are of the fire-tube type possesses advantages 
over the brick-set boilers in that there is not the air leakage into 
the furnaces, reducing the efficiency, that is often found in the 
boilers which require a brick setting. Furthermore, they do not 
need the costly brickwork. Internally-fired boilers are, on the 
other hand, unless provided with large furnaces, very poorly 
adapted for burning bituminous coals, which require large com- 
bustion chambers, in order that the flame from the burning coal 
cannot come in contact with the relatively cooler surfaces of the 
boiler and thus become cooled to such an extent that combustion 
ceases and the gases pass to the chimney unconsumed and con- 
sequently wasted. For this same reason, horizontal tubular boil- 
ers must be raised a good deal higher above the grate if bitumin- 
ous coal is to be burned than if anthracite is used. It is held by 
some engineers that bituminous coal gives the best results if it 
is burned in a furnace entirely separate from the boilers, so that 
the radiant heat from the fires will heat the fire brick lining, or 
checkerwork, which is sometimes introduced in the combustion 
chamber, to such an extent that the gases coming in contact with 
this highly heated brickwork are consumed before reaching the 
boiler. Horizontal return tubular boilers are seldom used for 
pressures as high as 150 pounds. 

Division of Heating Surface in Units. — The first problem con- 
nected with the design of a boiler plant is to determine accurately 
the maximum number of pounds of steam that will be used by 
the various engines, pumps, and other parts of the plant which 
will have to be supplied. As has been said, one square foot of heat- 
ing surface should be allowed in most boilers for every 3 pounds of 
water to be evaporated into steam from and at 212 degrees in an 
hour's time. With this proportion and sufficient draft and grate 
surface to burn the necessary amount of fuel, a boiler can easily 
be forced 33 1/3 per cent, over this capacity and maintain a good 
efficiency. It ought to be stated here, however, that the maximum 
evaporation of a boiler is limited mainly by the amount of coal 
which can be burned upon the grate. If the draft is sufficient 
a good boiler can develop a horse-power upon one-half of the 



16 STEAM POWER PLANTS. 

surface recommended. By dividing the total number of pounds 
of steam that are to be evaporated from and at 212 degrees per 
hour by 3, the amount of heating surface may be obtained with 
sufficient accuracy. 

The next step is the subdivision of this heating surface into the 
proper number of boilers. This is of considerable importance, 
for careful study may result in much saving in the first cost and 
in the cost of operation. For instance, if boiler capacity equiva- 
lent to evaporating 28,800 pounds of water from and at 212 de- 
grees an hour is required, 9,600 square feet of heating surface 
will be needed. If each square foot of heating surface may be 
overloaded 33 1/3 per cent., it is evident that if the 9,600 square 
feet were divided among four boilers, one boiler might be shut 
down for repairs or cleaning, which is frequently necessary, and 
the other three run at 33 1/3 per cent, overload and still evaporate 
28,800 pounds of water per hour. If the total heating surface 
was divided into three boilers, each of 3,200 square feet of heat- 
ing surface, two might not be able to run the plant alone, so a 
fourth or spare boiler would have to be supplied. This would 
manifestly be a poor division of power, as the money spent on 
the spare boiler would represent so much capital lying idle most 
of the time. The frequency with which a boiler is shut down for 
repairs or cleaning depends upon the attention given it and the 
character of the feed water. 

Importance of Proper Grate Surfaces. — To evaporate a given 
amount of water into steam it is necessary to generate a certain 
amount of heat by the combustion of fuel. The factors controll- 
ing the amount of heat generated are, the kind of coal, the 
amount of grate surface the boiler contains, and the draft. 
Ample grate surface therefore is highly desirable, particularly 
when boilers are to be forced. The draft affects the rate of com- 
bustion, as the amount of coal burned on each square foot of 
grate surface in an hour's time is usually called. Of the factors 
mentioned, that pertaining to the kind of coal to be used should 
be determined by an engineer before designing a boiler plant. 
He should investigate the cost of the various fuels available at 
the locality at which the boiler plant is to be constructed, and 
with these data and a knowledge of the relative evaporative 
power of the different fuels, he can determine in advance the 
cheapest kind of coal, the evaporative power and cost of each 




-Ninety-Sixth Street Powkk Station, Metropolitan Street Railway Company, New York. 
il. c. starrbtt, chief bxgi.nesr: f. s. pisrson. consulting engineer. 



STEAM POWER PLANTS. 17 

being considered, and construct the boilers so that it can be used. 
Many plants have been somewhat handicapped by the failure of 
their designer to consider this subject. Some coals, besides hav- 
ing less heating power per pound than others, cannot be burned 
at as high a rate of combustion on account of peculiar properties 
they possess. For instance, with the finer sizes of anthracite coal, 
it is impossible, unless mechanical draft is used, to burn more 
than a limited amount on a grate, as the particles pack together 
so closely that the air cannot get through the bed of fuel in suffi- 
cient quantity to permit a rapid combustion. Again a coal high 
in ash and sulphur is limited in the rate at which it can be burned. 
Of course, if only a limited amount of fuel can be burned on a 
grate, the grate has to be made large in proportion to the heat- 
ing surface, and when it is intended to burn a low-grade fuel, 
provision for a large grate ought to be made in the first place. 
If a plant is designed to burn a low-grade fuel, and it is desired 
to change to a fuel of better grade, this can be done by reducing 
the size of the grate by bricking off a portion of it. With a bet- 
ter fuel less coal would be burned, and it would probably be 
burned at a higher rate ; consequently so large a grate would not 
be needed. It might seem that it would not be necessary to re- 
duce the size of the grate to burn less fuel, but, although less fuel 
could be burned per square foot of grate by reducing the draft, 
yet it would probably not be good practice to do so, as it is neces- 
sary to burn some coals at a fairly high rate of combustion to 
secure the best result. Too slow combustion results in the par- 
tial burning of the gases, and this causes a loss. If it is certain, 
before a plant is constructed, that there never will be a desire to 
operate it with a lower grade of fuel than that for which it is 
designed, it would be foolish to provide larger grates than are 
necessary for this fuel, as boilers so constructed are frequently 
more expensive both in cost of construction and land occupied. 
A high rate of combustion is undoubtedly the best for many coals 
for the reason that the gases are much more thoroughly con- 
sumed when the furnace temperature is high. 

Proportioning Grate. — The ratio of the grate to heating sur- 
face varies with the kind of coal and the amount burned, as was 
explained in an earlier paragraph. From a knowledge of the 
number of pounds of water to be evaporated, and the amount one 
pound of a given kind of coal will evaporate under ordinary con- 



18 STEAM POWER PLANTS. 

ditions, the quantity of coal which must be burned in a given time 
can be calculated. If one knows the number of pounds of coal 
that must be burned, and the amount of coal that should be 
burned on each square foot of grate surface, in a given time for 
the normal rate of evaporation, the amount of grate surface can 
be determined. 

It remains, then, to provide sufficient draft, either by a fan or 
chimney, to produce not only the proper rate of combustion for 
ordinary demands, but also a higher one which will enable the 
boiler to operate with such' overload as may be thought necessary. 
The relative evaporative power of the better grades of a number 
of different coals is shown in the table, Pocahontas coal being 
placed at loo. These figures are approximate and should be used 
with some caution. The relative evaporation for the different 
coals shows what might be expected from the better grades of 
each kind of coal mentioned when fired by a good fireman under 
ordinary every-day conditions. The variation from these figures 
which might result from a difference in the quality of the coal 
from the same mine would be greatest with the Western coals, 
less with the Pennsylvania bituminous, and least with the semi- 
bituminous group. The anthracite, particularly the small sizes, 
might vary considerably on account of an abnormal amount of 
impurities present in the coal. The figures given in the table can 
be exceeded when all the conditions are favorable. 

Relative Value of Steam Coals. 

p, d oj^_> c3 rt fl a> o ■*-> 

Kind of coal. S ■3§S-'bl- °-l ^ = 

SI Ssflssi §-g is 

Pocahontas, W. Va.* 100 9.5 15 45 

Youghiogheny, Pa.t 92.5 8.7 17 48 

Hocking Valley, Ot 80 7.6 18 45 

Big Muddy, Ill.t 80 7.6 20 50 

MtOlive. Ill.t 67.5 6.4 20 45 

T.ackawanna. Pa. .J broken 87 8.5 15 35 

r>ackawanna. Pa. .J No. 1. buckwheat 73 7.5 13 32 

Lackawanna. Pa .t rice 63 7.0 12 30 

*Semi-bitumincus ; tBituminous ; JAnthracite. 

The table also shows about the amount of coal which should 
be burned per square foot of grate per hour under ordinary con- 



J 



^1 



I 



I 



'I 
ll 

: 

.4/1 



«a</ 






i 




Il\R-irORL> AND bPRINCriEID STREET RAILW \\ COMPAN\ 
E H KITFIELD ENGINEER 



STEAM POWER PLANTS. 19 

ditions; also, the ratio of heating to grate surface necessary for 
the boiler to develop its rated capacity when burning about the 
amount of coal stated and when each pound of coal is evaporating 
the quantities of water given in the table. Some authorities of 
considerable experience with Illinois coals advise higher rates of 
combustion than are recommended in the table for the best results. 
A grate proportioned in accordance with the data given can 
easily be reduced in size if found desirable. It is proposed to pro- 
vide sufficient draft, that equivalent to the pressure of 0.5 inch of 
water, to run easily a boiler proportioned according to the data 
given in the table at one-third over its rating. Five-tenths of an 
inch of draft might not be sufficient with the rice size of anthra- 
cite, if it is of poor quality, to enable a boiler proportioned ac- 
cording to the data in the table to operate with an overload of 
one-third. With the rice size of anthracite mechanical draft 
ought to be used. It is well to have a maximum draft of 0.6 inch 
of water available for the poorer Illinois coals. 

It is undoubtedly true that a better result will be obtained by 
higher rates of combustion than those given in the table, but if 
these are increased for the normal working of a boiler it will be 
necessary to have available a very intense draft, nothing less per- 
haps than that created by a fan, in order that there may be suffi- 
cient reserve draft to operate the boiler at much of an overload. 
In other words, if the rates of combustion are taken higher 
than those given for ordinary service, the draft must be 
made correspondingly greater to provide a reserve capacity in 
evaporative power. The high rates of combustion possible with 
mechanical draft are conducive to high furnace efficiency, but 
that is a subject which will be discussed later. 

Coal. — In an earlier paragraph attention was called to the 
necessity of proportioning boilers to burn the fuel which will be 
the cheapest. It seems well, therefore, to show in a general way 
some of the properties and the relative values of different steam 
coals. Such information can be misleading on account of the 
variations that exist not only in different coals, but in coal mined 
from the same seam. Nevertheless an approximate relation can 
be given for the better grades of several different coals that are 
typical of the kinds most used. What the poorer grades of coal 
of some of these kinds will do, it is impossible to predict. The 
steam coals used in the eastern and middle parts of the United 



20 STEAM POWER PLANTS. 

States may be divided into anthracite, bituminous and semi-bit- 
uminous classes. A coal is classified in these groups according 
to the relative proportions of fixed carbon and volatile hydro- 
carbons that it contains. The hydro-carbons are those gases 
given off by certain coals when they are heated moderately. Semi- 
bituminous coals contain less than 25 per cent, hydro-carbons and 
bituminous coals 25 to 60 per cent. The former are the best 
steam coals for the reason that when the hydro-carbons are more 
than 20 per cent, of the fuel composition, the heat value of the 
fuel becomes less, for then the hydro-carbons contain more or less 
oxygen while with less than 20 per cent, hydro-carbon, the vola- 
tile gases are mostly hydrogen and the coal therefore has a higher 
heat value. The percentage of hydro-carbons in anthracite coal 
is very small. 

Semi-Bituminous Coals. — This group contains the finest steam 
coals mined in the United States. They are found mainly in Vir- 
ginia, West Virginia and Maryland. The ash varies from 3 to 8 
per cent., while the coals contain about 14,500 heat units per 
pound. The coals of this group are much more uniform in heat- 
ing power and evaporation than those of any other, but there is 
a variation in some of them owing to the fact that care is not 
taken to exclude impurities which affect their heat value. This 
group of coals includes the Pocahontas, New River, Cumberland 
(George's Creek), and Clearfield varieties. The value is about 
in the order named, Pocahontas and New River probably being 
the most constant in quality. Placing the evaporative power of 
Pocahontas and New River at 100, none of the other coals would 
be hardly less than 95. 

Bituminous Coals. — These are found in Pennsylvania, Ohio, 
Kentucky, Tennessee, Indiana, Illinois, Missouri and other states. 
They differ widely in heating power, not only one coal from 
another, but a great difference is also found in coal from the 
same mine. The bituminous coals are divided into two classes, 
caking and non-caking. The Indiana, Illinois and Missouri coals 
are of the caking variety, which on burning becomes pasty and 
forms into lumps that greatly impede the fire unless broken up. 
Certain western coals have to be burned at a comparatively high 
rate of combustion, about 20 pounds of coal per square foot of 
grate per hour, otherwise it is difficult to keep the fire from go- 
ing out. The Pennsylvania coals are much the best for steam 



STEAM POWER PLANTS. 21 

purposes, and the Ohio coals are usually better than those found 
farther west. 

Anthracite Coal. — This is mined chiefly in Pennsylvania, al- 
though quite a little is found in the far West. It is principally 
composed of pure carbon and its heat value is dependent mainly 
on the amount of earthy matter mixed with it when sold. The 
percentage of earthy matter is naturally greater in the smaller 
sizes. Anthracite coal is classified according to size into lump, 
broken, tgg, stove, chestnut, pea, numbers i and 2 buckwheat, rice 
and barley. Pea coal is about as large as is usually used for steam 
purposes. The larger sizes of this coal, that is, the chestnut size 
and over, are about equivalent in evaporating power to Pittsburg 
bituminous coal. The smaller sizes require a very strong draft 
because the particles of coal, being small, pack together so that 
the air cannot get through the bed of fuel to cause rapid combus- 
tion. It is therefore impossible with natural draft to burn more 
than a very limited amount per square foot of grate, and it is in- 
convenient and costly to provide boilers with a sufficient grate to 
burn buckwheat or the smaller sizes with the draft due to an or- 
dinary chimney. It is necessary, therefore, if this grade of fuel 
is to be used to construct a 125-foot, preferably 150-foot chimney, 
or to employ mechanical draft. Rice and the smaller sizes can 
hardly be burned without mechanical draft. With 0.5 inch of 
draft from 16 to 18 pounds of good clean buckwheat coal can be 
burned per square foot of grate per hour. 



Chapter III. — Design of Horizontal Return Tubular 
Boilers and Boiler Specifications. 

The horizontal return tubular boiler is used to a far greater ex- 
tent than any other type in the United States at the present time 
and it is intended in this chapter to give some general rules for 
designing boilers of this type. Another well known boiler of the 
fire tube type is the Manning, which is a vertical boiler with un- 
usually long tubes rising from a high combustion chamber sur- 
rounded by water. It has been used successfully to a considerable 
extent in New England. Various boilers of the fire-tube type of 
special design have been illustrated from time to time in technical 
papers, but the use of these boilers is so limited compared to the 
horizontal return tubular boilers that they will not be further 
alluded to. A sectional view of a typical setting for a horizontal 
return tubular boiler is given in Figure 5. The method of pro- 
portioning the different parts of a boiler of this type follows : 

Thickness of Shell. — One of the most satisfactory rules for 
determining the thickness of shell necessary in boilers of the fire- 
tube type, is that used by the steam boiler inspection department 
of the City of Philadelphia. The rule is as follows : 

Working pressure = 2Tts -^- Df, 
in which 

T = the ultimate tensile strength of the plate in pounds per 
square inch. 
t = the thickness of the plate in inches, 
s = the efficiency of the longitudinal joint. 
D = the diameter of the boiler in inches, 
f = the factor of safety. 

The factor of safety is usually taken at 5. With a tensile 
strength of 60,000 pounds and a joint efficiency of 80 per cent, 
the rule shows that with a 9/16-inch plate, which is about as thick 
as is commonly used for the shell of an externally fired boiler on 
account of the resistance that a thicker plate offers to the transfer 
of heat at the girth seams of the boiler, the highest working 



STEAM POWER PLANTS. 



23 




24 



STEAM POWER PLANTS. 



pressure that can be carried in a boiler 6 feet in diameter is 15a 
pounds. A few horizontal return tubular boiler plants have been 
designed to carry a steam pressure of 150 pounds but it is better 
to use water-tube or internall}' fired fire-tube boilers if this or a 
higher pressure is to be carried unless the boilers are designed 
by an expert. 

Braces. — Braces are used in horizontal tubular boilers to 
balance the pressure exerted on those parts of the heads of the 
boiler above and below the tubes and not close to the shell. If 
these parts are not braced, the pressure would cause the flat head 
to bulge outw^ard. For a distance of 3 inches from the shell, and 
for a distance of 2 inches from the tubes, the head is usually con- 
sidered to be sufficiently stiffened by the circumferential joint and 
the tubes not to need other bracing. Figure 6 shows one of the 
heads in a horizontal tubular boiler and the part which has to be 
braced is indicated. Braces used in this work are usually of two 
kinds, the direct or through stay or brace, whicli extends entirely 




Figure 8. — Connecting Direct Braces. 



through the boiler and joins the heads together, and the diagonal 
or crow-foot brace. This latter is shown in Figure 7. The head 
is connected to the adjacent shell by it. The diagonal brace is 
preferred by the boiler inspection companies, as it is much easier 
to get inside of a boiler to inspect the interior with this brace than 
with the direct type. If the latter are used the»y should be suffi- 
ciently separated to allow a man entering the manhole opening to 
pass between them. The braces should be distributed uniformly 
over the area they are intended to support. Figure 5 shows the 
manner in which diagonal braces may be distributed over the 
head. Five direct braces are sometimes used, three being placed 
in a lower row and two above, all being symmetrically placed with 
reference to the center. When direct braces are used the heads 
are frequently further stiffened by channel iron or angle irons 
riveted to the heads as shown in Figure 8. If manholes are 



STEAM POWER PLANTS. 



25 



placed in one of the heads of the boiler the heads below the tubes 
should be braced. 

In determining the number and size of braces the area in square 
inches of the surface to be stayed must be calculated and then 
the total pressure on this area. This latter divided by 7,500 will 
give the cross sectional area in square inches that must be pro- 
vided in all of the braces combined, 7,500 pounds per square inch 
being the greatest strain to which a brace should be subjected. 
Cutting a thread on the end of the braces for the nuts, reduces 
the area of metal somewhat and this should be taken into account. 
Sometimes the ends of the braces are upset, that is, heated and 
hammered at the end so that their diameter is increased slightly 
where the thread is to be cut. 

With diagonal braces the pull exerted is not perpendicular to 
the head of the boiler. Hence the area of the brace should be 




Figure 9. — Method of Suspending Boiler. 



calculated by dividing the surface supported by 7,500 and then 
increasing the result by multiplying the quotient obtained by the 
length in inches of the brace divided by the distance in inches 
that the head is from the point where the brace is attached to the 
shell. Referring to Figure 7 the length of the brace is the dis- 
tance A B and the distance from the head to the point where the 
brace is attached is the distance C B. The ratio A B : C B is the 
amount that the brace should be increased. For instance, if the 
surface to be stayed should require the pull of a brace i square 
inch and the length A B should be 48 inches and the length C B 
40 inches, then the area of brace actually required would be 
I X 48 -^40 = 6-^5 =1 1/5 square inches. 

Supporting Boilers. — For many years the practice has been to 
support boilers by riveting two pair of lugs on the sides of the 



26 



STEAM POWER PLANTS. 



shell, as in Figure 6, and supporting them on cast-iron plates built 
into the setting, rollers being placed under the pair of lugs in the 
rear, so that the movement due to expansion will be toward the 
rear. The principal objection to this plan is that the settlement 
of the walls of the setting, which is almost sure to occur, often 
throws almost the entire work of supporting the boiler on two 
lugs. A number of engineers suspend a boiler by riveting straps 
to the shell and passing hooked rods through them and through 
cast-iron plates resting on I-beams laid across the top of the set- 



TABLE I.- 


— TUBI 


D SPA' 


CING AN 


D HEATING 


\ SURI 


rACE 


IN HOI 










TUBULAR BOILERS. 












Tubes 


, 


i° 


g 


Tubes. 

center to 

center. 


n 
^h 


.9 


t 










a; 






c5 


at 








s 


S 


1 

■ s 


Id 


111 




'0$ 


i 

h 


A. 


B. 








D. 


E. 


p. 


G. 


48 


3 


46 


1.94 


43.67 


9x14% 


41^ 


4 


6y2 


50 


3 


52 


2.19 


48.69 


9xl4y2 


4% 


4 


6% 


52 


3 


54 


2.28 


50.58 


9 X 14y2 


4y4 


4 


714 


54 


3 


60 


2.53 


55.60 


9 X 14yo 


4% 


4 


Tya 


56 


3 


64 


2.70 


59.06 


11x15 


4y3 


4 


8 


58 


3 


70 


2.95 


64.09 


11x15 


4y3 


4 


syt 


60 


3 


76 


3.21 


69.11 


11x15 


4y2 


4 


8V2 


48 


3y2 


34 


1.97 


38.68 


9xl4y2 


5 


4y3 


ey^ 


50 


31/2 


38 


2.20 


42.66 


9 X 14y2 


5 


4y2 


eys 


52 


3% 


46 


2.67 


50.31 


0xi4y3 


5 


4y2 


TV,. 


54 


SVa 


47 


2.73 


51.53 


9xl4ya 


5 


4y2 


7% 


56 


31/2 


50 


2.90 


54.60 


11x15 


5 


4y3 


7y2 


58 


3y2 


52 


3.02 


56.74 


11 xl5 


5k 


4y2 


7% 


60 


31/3 


56 


3.25 


60.71 


11x15 


5% 


4y3 


8Vi 


62 


31/3 


60 


3.48 


64.72 


11 xl5 


5% 


4y2 


8y2 


64 


3y2 


64 


3.71 


68.67 


11x15 


5y2 


4y2 


9 


66 


3y2 


70 


4.06 


74.49 


11x15 


5y2 


4y2 


QVi 


54 


4 


36 


2.75 


46.17 


11x15 


6 


5 


7 


56 


4 


38 


2.90 


48.59 


11x15 


6 


5 


7y4 


58 


4 


40 


3.05 


50.99 


11x15 


6 


5 


7% 


60 


4 


47 


3.59 


58.63 


11 xl5 


6 


5 


8 


62 


4 


49 


3.74 


61.04 


11x15 


6 


5 


8Vi 


64 


4 


51 


3.89 


63.45 


11 xl5 


6 


5 


s% 


66 


4 


56 


4.27 


69.00 


11x15 


6 


5 


9 


68 


4 


62 


4.73 


75.59 


11 xl5 


6 


5 


9ya 


70 


4 


64 


4.88 


78.01 


11 xl5 


6 


5 


9% 


72 


4 


74 


5.65 


88.79 


11 xl5 


6 


5 


101/4 






10 to 12 
10 to 12 
10 to 12 
10 to 12 
10 to 12 
10 to 12 
10 to 12 
12 to 14 
12 to 14 
12 to 14 
12 to 14 
12 to 14 
12 to 14 
14 to 16 
14 to 16 
14 to 16 
14 to 16 
16 to 20 
16 to 20 
16 to 20 
16 to 20 
16 to 20 
16 to 20 
16 to 20 
16 to 20 
16 to 20 
16 to 20 



ting. Figue 9 shows this construction. This is one of the best 
methods. If it is used it is well to have an iron plate of generous 
size between the beams and the setting for the former to rest 
upon. 

Tubes. — Tubes should not be so closely spaced in a boiler as to 
interfere with a proper circulation of water in them. Three, y/2 
and 4-inch tubes are commonly used in horizontal tubular boilers. 



the last bein; 



generally used 



in large-size boilers, the size de- 



STEAM POWER PLANTS. 



27 




Figure 10. 



creasing with the diameter of the boiler. Barrus states that a 
certain ratio of tube area to grate surface is necessary to give the 

best result with different fuels, 
a ratio of nine to one or ten to 
one being proper for anthracite 
coals and six to one or seven 
to one for bituminous coals, 
the difference being due to the 
large volume of gases with bit- 
uminous coals, which requires 
a large area in the tubes to pass 
the gases at the proper velocity 
for giving off their heat. 
Tubes should be placed in ver- 
tical rows and not staggered. 
They should be located as far 
apart as the number necessary 
to put in the boiler will permit; 
lor this will permit a better 
circulation, which is essen- 
tial when the boiler is oper- 
ating at high rates of combus- 
tion. 

By means of Table I. and 

Figures lo, ii and 12 the 

proper method of locating and 

spacing tubes in return tubular 

boilers may be found. The 

three figures refer respectively 

to 60-inch boilers with 3, 3^ 

and 4-inch tubes. These data 

have been taken from Mr. W. 

M. Barr's work, "Boilers and 

Furnaces." Figure 8 has also 

een taken from the same 

source. In using Table I. to de- 

the ENaiNcexiNo REcoRo. tcrmiuc thc uumbcr and location 

Figure 12. of tubes for boilers of different 

diameters than those shown in the figure, a drawing of the tube 

sheet should be made on which the centers of the tubes can be 




Figure 11. 




28 



STEAM POWER PLANTS. 



located from the data given in the tables. Barr states that ''the 
distance from the side of a tube to the inside of the boiler shell 
should not, in the case of a 36-inch boiler, be less than 2 inches, 
for a 48-inch boiler it should not be less than 23^ inches, and for 
a 50-inch boiler and larger, the distance should be not less than 3 
inches, to secure good water circulation." Calculations have been 
made showing the heating surface per lineal foot of boiler for 
each of the different sizes given in the table, also the usual length 
of each. The tube area is also given and this may be useful in 
comparing the tube area with the size of grate. The method of 




Figure 13. 



determining the proper amount of heating and grate surface was 
explained in the preceding chapter. 

Riveting. — In Tables II., III. and IV. there are given propor- 
tions of riveted joints recommended by the Hartford Steam 
Boiler Inspection & Insurance Company, which are published 
through the courtesy of that corporation. The efficiencies for 
the different joints, given in the table, are to be substituted in the 
formula for determining the thickness of shell plates. The dimen- 
sions to which the letters in Table IV. refer are shown in Figure 
13. Butt joints are far superior to lap joints as there is not 



STEAM POWER PLANTS. 



29 



the tendency of the plate to crack on a Hne parallel with and near 
the rivets. The joints are designed for metal having a tensile 
strength of from 55,000 to 60,000 pounds, and the efficiency cal- 
culations are based upon the latter figure. The shearing strength 



TABLE II.— DIMENSIONS OF DOUBLE-RIVETED STAGGERED SEAMS. 



Thickness Diameter 

of sheet, of rivets 

inches. inches. 

M ii 



il 



Diameter 
of rivet 
holes, 
inches. 

-it 
\% 

1 



Pitch, 

inches. 

2% 

oH 

3t\ 
3.32 



Lap, 

inches. 

4% 
5 



Distance 
between 
rows of 

rivets. 

inches. 

Ill 

s 

2i% 



Edge of 

sheet to Efficiency, 
pitch line, — Weak- 
inches, est part. 



Hi 



0.739 
0.717 
0.711 
0.687 
0.G77 



Single Riveted Girth Seams Used with Above Longitudinal Seams. 

HUH 2i^5 m 0.545 

fs M it 



1'' 



2% 



'^1% 



0.494 

0.49 

0.466 

0.449 



TABLE III. — TRIPLE-RIVETED LAP JOINT. 



Thickness Diameter 

of sheet, of rivets, 

inches. inches. 



* II 



U 



S 



Diameter 

of rivet 

holes, 

inches. 

s 

it 



Pitch, 
inches. 



m 



Lap, 
inches. 



611 

7]% 



Distance 

between 

rows of 

rivets, 

inches. 



U 



Edge of 

sheet to 

pitch line, 

inches. 

IM 
il4 



0.77 
0.76 
0.75 
0.75 
0.746 



Single 


Riveted Girth 


Seams Used 


WITH Above Longitudinal 


Seams. 


M 


i 1 


2t5 


2^ 





0.456 


ft 


2)4 


2^ 




0.419 


2}^ 


2/s 


.... .... 


0.412 


ti 


% ^i 


2% 


2-}i 




0.42 


if 1 


^H 


3 


.... 


0.398 


TABLE 


IV.— TRIPLE 


RIVETED BUTT JOINT WITH DOUBLE WELT. 


less 
eet, 

s. 

ter 
ets. 


|l-s i§^^ 










»jfl 0) 0) > Ol 


IJ 'S 75 S |3 <!> 










■S^-S a-s-g 


a'^ii -g^-g 










i-oB l^oa 


50^ go.a 


A. B. 


C. 


D. E. 


F. 


a II 
s ft 


M ¥ 


78 m 


2% 


21^ 2!4 


134 0.88 




2]^ 


2?, 2/, 


U\ 0.75 


1''^ i 


m 


i f 


ip 0.86 
1^ 0.866 


Single 


Riveted Girth 


Seams Used 


WITH Above Longitudinal 


Seams. 






Diameter 








Thickness 


Diameter 


of rivet 








of sheet. 


of rivets. 


holes, 


Pitch, 


Lap, 




inches. 


ipches. 


inches. 


inches. 


inches. 




ft 






2 
2 


2^ 


0.446 
0.438 


i 


i*» 


2§ 


3 


0.444 
0.442 



allowed to the rivet steel per square inch of section in single 
shear, when used in steel plates, is 38,000 pounds, and a rivet 
in double shear is considered to be equivalent to 85 per cent, addi- 



30 STEAM POWER PLANTS. 

tional. Rivet steel is allowed for shearing strength 45,000 pounds 
per square inch of section. In the calculations for the efficiency 
the rivet is assumed to fill the hole and the diameter of the rivet 
hole, not that of the rivet, is therefore used. The efficiency of the 
girth seams given in the tables need not be considered in determ- 
ining the thickness of shells of boilers. 

Boiler Settings. — Figure 5 shows a longitudinal and cross-sec- 
tion of popular form of setting for return tubular boilers. It 
should be constructed of hard red brick, laid in lime or cement 
mortar, and the entire setting ought to be lined with fire brick 
with every fifth course laid as headers, so that any part that might 
become damaged could be easily renewed without taking out the 
entire lining. Sometimes, to economize, the furnace as far as the 
bridge wall only is lined with fire brick. The fire brick should 
be laid in fire clay, using as little of it as possible. In the draw- 
ing the grate has a width equal to the diameter of the boilers and 
the side wall is battered so as to leave a space of 3 inches at the 
level where the setting closes into the boilers. The side walls are 
provided with air spaces, as shown, which are necessary to pre- 
vent the wall from cracking. 

If fire brick, backed with common brick, is used the side walls 
have to be 13 inches thick and the air space should be about 2 
inches wide at the bottom and diminish as its sides converge. 
Two 13-inch walls and a 2-inch air space make the entire thick- 
ness of the wall between the boilers 28 inches. This diminishes 
at the top as shown. It is sometimes difficult with low-grade fuels 
and natural draft to burn sufficient coal on the grate of a hori- 
zontal tubular boiler to obtain as high evaporation as might be 
needed, hence it is desirable, if these boilers are apt to be fired 
with such fuel, to place the boilers a little farther apart and make 
the side walls perpendicular and at a distance apart at the grate 
equal to the diameter of the boiler plus 6 inches. This makes 
the grate 6 inches wider and increases its surface materially. If 
a boiler is constructed in this way, it is a simple matter to dimin- 
ish the size of the grate by bricking off the sides and rear. It is 
difficult to fire a grate more than 6 feet deep, although they are 
sometimes made 7 feet in depth, in large boilers. Furnaces over 
5 feet wide should have two fire and two ash-pit doors. 

The top of the bridge wall of the boiler is usually about 10 or 
12 inches from the bottom of the shell, and the space behind may 



STEAM POWER PLANTS. 31 

be filled with earth and paved with common brick or left empty. 
Curving this combustion chamber to conform with the shell only 
reduces its size, which is a disadvantage with bituminous coal and 
of no use with other kinds. The rear wall should contain an air 
space and be provided with a clean-out door about i6 x 20 inches. 
The wall should be located at a distance of 18 to 24 inches, de- 
pending on the size of the boiler, from the back head. 

The back connection, that is, the connection between the rear 
wall and the head, is a source of more or less trouble on account 
of the expansion and contraction of the boiler, and the difficulty 
of making a joint that will remain tight. One method is to spring 
an arch across having one end resting on the wall and the other 
upon an angle iron riveted to the back head of the boiler. The 
arch consists of brick resting in an iron framework. The Hart- 
ford Steam Boiler Inspection & Insurance Company uses an arch 
somewhat similar to that shown in Figure 5. 

The grate should be at a level of 24 inches above the floor and 
the shell from 28 to 30 inches above the grate with anthracite coals 
and from 36 to 42 inches if bituminous coals are to be burned, as 
the gases from the latter do not burn properly if the flame comes 
in contact with the cooler boiler surfaces. The floor of the ash 
pit should be paved with brick laid on edge and flushed with a 
thin cement mortar so as to be water tight. This floor is usually 
3 to 6 inches below the floor of the boiler room. 

An interesting horizontal tubular boiler is shown in Plate 4 and 
Figure 14. This boiler was built for a steam pressure of 185 
pounds per square inch from the plans and specifications of Dr. 
E. D. Leavitt, consulting engineer. A full description of it 
appeared in The Engineering Record of May 18, 1901. 

Boiler Specifications. — It was thought advisable to print one 
or two typical specifications for horizontal return tubular boilers 
and to outline a method to be pursued in purchasing water tube 
boilers, the difference in construction of boilers of the latter type 
making it necessary for the specification to be mainly a general 
description of what is wanted and what the boilers are to do. 

In the first form of specification printed, which calls for the 
delivery and setting of a boiler, those clauses that relate to the 
prosecution of the work, the removal of rubbage after its comple- 
tion, remuneration for a change in the plans, interpretation of 
drawings, etc., are omitted. The specification is divided into sec- 



32 



STEAM POWER PLANTS. 



tions and in some cases comment or explanation follows a sec- 
tion. A form of specification for high-grade work follows : 

Intent of Specifications. — It is the intent and purpose of these specifica- 
tions to provide for the furnishing and installation of a complete boiler 
plant comprising the boilers, setting, grates, fronts, feed and blow-off pip- 
ing, gauges, smoke breeching, flues, dampers, and such details as are here- 
inafter specified, all complete and erected ready to generate steam. 



ffS' 



^Isf S'7%" 36 Equal Spaces, 2.864-" Pitch 

— - — I '^'19' Riveta. - '' 



fm^\\N\M 







Enlarged Sec+ion o-P Head and Shell . 



Longitudinal Joint, Rear Course. 




Hanger. 



Manhole Cover and Yokes . 
Figure 14. — Details Leavitt Boiler. 



Section B-B. 

The ENQrNCEniNQ RECORD. 



Materials. — The shells and heads of the boiler are to be constructed of 
open hearth steel having a tensile strength from 55,000 to 65,000 pounds 
per square inch, with a yield point not less than one-half the tensile 
strength and an elongation of 25 per cent, in eight inches. (See note be- 
low.) Test specimens cut from the plates must, when cold, be capable 
of being bent 180 degrees flat on themselves without fracture on the outer 
side of the bent portion, also, after being heated to a light cherry red and 
quenched in water of a temperature between 80 and 90 degrees Fahrenheit. 



STEAM POWER PLANTS. 



33 



For the bending tests the test specimens shall be IVz inches wide, if pos- 
sible, and for all material % inch or less in thickness, the test specimen 
shall be of the same thickness as that of the finished material from which 
it is cut; but for material more than % inch thick, the bending specimen 
may be only % inch thick. One specimen for the cold bending and one 
for the quenched test to be furnished from each plate and marked for 
identification. Specimens for the tensile tests of the dimensions shown 
in the upper illustration in Figure 15 are to be cut from each plate marked 
for identification and given to the engineer. 

Rivet steel shall have a tensile strength from 45,000 to 55,000 pounds 
per square inch, the yield point to be not less than one-half the tensile 
strength and the elongation 28 per cent, in eight inches. Rivet steel of 
the full size as rolled shall pass the same bending tests as specified for 



>• 



^Ahnnr\ ^ ^WdtTess than 9'^228.6mr 



> 



■ ■^^ 

i^ 



J_l 



5^ 

-^'t: — 7f\ — 



\210^ 



\^25.40mm Xp;^c§ 
l3"^^Z20mm Ab-^—- 



':i 









2'^- 57 /5 mm 



mrri^ 



t 



^k% ^4-^9.05 ^ 




Figure 15. — Dimensions Test Specimens. 



shell plates. Two tensile test specimens shall be furnished from each melt 
of rivet rounds. In case any one of these develops flaws or breaks out- 
side of the middle third of its gauged length, it may be discarded and an- 
other test specimen substituted therefor. Two cold bending specimens 
and two quenched bending specimens shall be furnished from each melt of 
rivet rounds. 

Note. — The foregoing section upon materials is an abstract of the 
standard specification for boiler plate and rivet steel adopted June 29, 
1901, by the American Section of the International Association for Test- 
ing Materials. Reference to the chemical properties of the steel has been 
omitted. A variation in the elongation with different thicknesses of plate 
is provided as follows : For each increase of Vs inch in thickness above 
% inch, a deduction of one per cent, shall be made from the specified 



34 STEAM POWER PLANTS. 

elongation. For each decrease of 1-16 inch in thickness below 5-16 inch 
a deduction of 2V2 per cent, shall be made in the specified elongation. 

Shell and Heads. — The shell plates are to be — inches thick, the heads — 
inches thick. The shell is to be in three courses (or two courses if the 
boiler is small enough), and the middle one must be of the smallest diam- 
eter. The edges of the plates must be planed before they are put together 
and caulking must be done with a round-nosed tool. Heads must be 
flanged to a radius not less than 1^/^ inches and they must be annealed after 
flanging. The flange must be free from cracks and flaws. 

Riveting. — The girth seams are to be of the single-riveted lap-joint type, 
the pitch of the rivets to be — inches ; lap — inches and rivets — inches 
in diameter. The longitudinal seams are to be placed well above the fire 
line, and to be of the butt type triple riveted with double welt, as shown 
in the drawing (which the engineer should supply). The rivet holes are 
to be drilled or punched Vs inch small and afterward drilled or reamed 
out to full size. A reamer must be used instead of the drift-pin. The 
burr is to be removed and the rivets driven by a hydraulic or pneumatic 
riveter as far as possible. 

Note. — Some specifications intended for high grade work demand that 
the rivet holes shall be punched % inch small and the shell then rolled 
and the lapping ends bolted together while the holes are drilled out the 
full size. This insures that the holes in one end of the sheet shall come 
opposite those in the other end and much better riveting will be the result. 
Oftentimes the holes are punched out to the full size, but authorities unite 
in saying that the metal immediately surrounding a punched hole is weak- 
ened. Hence it is better to punch the holes small and drill or ream them 
out to full size. 

Bracing. — The heads are to be braced to the shell by — radial solid 
crow foot braces, — on each head distributed as shown on drawing. The 
braces must be of — inch stay bolt iron at least 3 feet long, forged up 
without a weld and be connected to the shell by two — inch rivets. Each 
brace must be so located as to lie in a plane passing through the axis of 
the boiler. 

Note. — If through braces are used, their number and diameter should 
be given and their location shown on a drawing. If the ends of the 
braces are to be upset, or if channel or angle irons are to be riveted to the 
heads to stiffen them, it should be so stated, and their weight and dimen- 
sions specified, or shown by a drawing. 

Tubes. — The tubes are to be — in number, — inches in diameter, — 
feet long, of the best charcoal iron lap welded or of steel. The tube holes 
in the head are to chamfered and the tubes are to be carefully expanded 
and beaded over at the ends. The tubes are to be located as shown in a 
drawing (which the engineer should supply). 

Manholes. — A pressed steel manhole frame, 11 by 15 inches, is to be 
riveted to the top of each boiler, with the long diameter girthwise (in a 
position indicated by the engineer), and another is to be riveted to the 
front head below the tubes. The usual pressed steel manhole plate, gasket, 
yoke and bolt is to be provided for each. 

Hand-hole. — A 4 by 6 inch hand-hole is to be placed in the back head 
below the tubes. The plate, gasket, yoke and bolt is to be provided. 

Nozzles. — Each boiler is to have two — inch cast-iron nozzles riveted to 
the boiler in the middle of the front and rear courses. The nozzles are to 
be drilled to fit the A. S. M. E. standard flange schedule. 




Sec+i 





Longi+odinal Elevation 



Plate 4. — Boilers at Plymouth Cordage Company, 
dr. e. u. le.^vitt. engi.veer. 



STEAM POWER PLANTS. 35 

Lugs. — The boiler is to be supported on the brickwork by four heavy 
cast-iron lugs riveted to the shell, one pair to the front and the other to 
the rear course. The front lugs shall rest upon bearing plates. Three 
1-inch rollers shall be placed under each rear lug between it and the bear- 
ing plates, which are also to be provided. 

Note. — If the boiler is to be supported by straps from beams laid across 
the top of the setting, it should be specified and a drawing showing the 
detail of the method of hanging the boiler given. 

Feed Pipe. — The contractor is to supply and connect a — inch steel (or 
brass) feed pipe that is to pass through a brass bushing in the front head 
of each boiler, at one side and 3 inches above the tubes and extending to 
the rear of the boiler. 

Tools. — Each boiler is to be provided with a fire shovel, slice bar, hoe 
and poker. The boilers are to be provided with one tube scraper and the 
necessary hose and nozzle for blowing soot from the interior of the tubes.- 

Blow-off. — A blow-off connection is to be provided at the bottom of 
each shell at the back end. The — inch opening in the shell is to be 
tapped to receive a — inch blow-off pipe and the opening is to be rein- 
forced by a — inch steel plate riveted to the shell. The blow-off pipe is 
to be protected by a fire-clay tube and run in the manner shown in the 
drawing to a blow-off main provided for in another contract. The boiler 

contractor is to supply a — inch blow-off cock of make for each boiler 

and the fire-clay tube for protecting the blow-off pipe. 

Castings. — Each boiler is to be provided with a cast-iron flush front, 
cheek plates, mouth plates, one (or two) fire and one (or two) ash pit 
doors and clean-out door for rear wall, arch plates, grate bars, bearing 
bars, T bars for back connection, tie rods, wall braces, etc. The grate 
bars shall contain 50 per cent, air space and are to fit a grate — by — 

inches and to be suitable for burning coal. The fire doors are to be 

fitted with registers and perforated linings, the ash pit doors with registers, 
and the clean-out door a lining. 

Fittings. — Each boiler to be furnished with the following fittings, which 
are to be connected : One water column upon which can be mounted a 
steam gauge, gauge cocks and gauge glass connected to the boiler by 
l%:-inch pipe; three — inch gauge cocks; one — inch gauge glass; one — 
inch steam gauge of make and provided with stop cock and siphon. 

Hydrostatic Test. — The boiler must be made sufficiently tight to stand 
without leaking when subjected to a hydrostatic test of a pressure 331-3 
per cent, in excess of the normal working pressure of — pounds. 

Setting. — The boilers are to be set in accordance with the accompanying 
drawing. The settings are to extend 6 inches below the floor level and 
are to be of the best brick laid in lime mortar and the entire setting is to 
be lined with the best quality of fire brick laid in fire clay and with every 
fifth course set as headers. The setting is to be closed in at the shell 5 
inches above the center line of the boilers, except at the lugs where the 
setting closes in two courses below the lugs. The boilers are to be sup- 
ported by lugs as previously stated and care must be taken that bearing 
plates are placed level and that rollers under the rear and middle lugs are 
placed perpendicular to the axis of the boilers. The foundations for the 
setting are to be laid by the contractor. 

Smoke Flue and Chimney. — If an iron chimney is to be used, 
some believe, in small work, that it is best to put the boilers, 



36 STEAM POWER PLANTS. 

smoke breechings and flue, damper and damper regulator and 
chimney in the boiler contract for the reason that all of them 
affect the operation of the boiler. The method of proportioning 
the chimney, etc., is discussed later. The boiler specification 
therefore should indicate the thickness and dimensions of the 
smoke flue. Provisions should be made for a damper in the up- 
take of each boiler that may be closed when the boiler is under- 
going repairs. There should be a damper in the main flue and 
this should be under the control of an automatic damper regu- 
lator which opens or closes the damper according as the steam 
pressure is respectively below or above the normal. The smoke 
flue should have doors through which the soot may be removed 
when necessary. 

The following specification for a horizontal return tubular 
boiler, without the setting, was prepared by Messrs. Dean and 
Main, a well known firm of mill engineers, and it is printed 
through their courtesy. The author believes it to be an excellent 
specification for the purpose intended. It will be noticed that it 
calls for the construction and delivery of the boilers only. Ap- 
pended to the specification was a blue print reproduced in Fig- 
ure i6. 

SPECIFICATIONS FOR THREE 78-IN. HORIZONTAL RETURN TUBULAR BOILERS 

FOR — 

Proposals. — Proposals will be received by Dean & Main, Exchange 
Building, Boston, Mass., for building and delivering three horizontal re- 
turn tubular boilers of the following general dimensions : 

Working pressure by gauge, lbs 125 

Inside diameter of end rings of shell, in 78 

Thickness of shell, in 7/16 

Length of tubes, ft 18 

Diameter of tubes, in 3 

Number of tubes 166 

Width of grate, ft 7 

Length of grate, ft 7 

Height of center of boilers above floor, ft 8.25 

Distance from c. to c. of boilers, ft 9 

Height front of grate above floor, ft 2.5 

Height back of grate above floor, ft 2 

Thickness of heads, in 1/2 

Diameter of rivets, in ,... 7/8 

Heating surface, sq. f t 2,376 

Grate area, sq. ft 49 

Contract Price. — The price is to be stated to cover the manufacture of 
the boilers and their deliverv with the accessories furnished on cars. 



STEAM POWER PLANTS. 



37 



Quality of Materials and Workmanship.— It is the intention that the 
materials and workmanship of the boilers shall be of the best. A repre- 
sentative of Dean & Main is to have the privilege of inspecting the boilers 
during their construction. 

Plates.— The plates are to be of the best quality of open hearth acid or 
basic steel, having the following qualities : 

Elastic limit per sq. in. not less than 30,000 lbs. 

Ultimate strength per sq. in 52,000 to 60,000 lbs. 

Elongation in eight inches not less than. . , 27 per cent. 

Sulphur not to exceed 0.35 per cent. 

Phosphorus not to exceed 0.30 per cent. 

The plates are to be free from laminations and surface defects, and also 
to stand cold and quench bending tests flat down without showing a sign 




Figure 16. 



of fracture. The tests are to be made by (name of testing laboratory) at 
the expense of the purchaser. 

Joints. — The circular joints are to be single riveted and lapped. The 
longitudinal joints are to be butted and provided with inside and outside 
covering plates. The inside and outside covering plates are to be double 
riveted each side of the center of the joint, and the inside plate will be 
extended sufficiently beyond the outside on both sides of the joint to re- 
ceive on each side two additional rows of rivets passing through it and 
the boiler shell. Thus there will be eight rows of rivets in each long- 
itudinal joint. The outer rows of rivets will have double and triple the 
pitches of the other rows. 

There will be one longitudinal joint in each plate. The boiler is to be 
made of three plates, and the joints of the two end plates will be above 
the water line on one side of the boiler and that of the center plate above 
the water line on the other side. If practicable it is preferred to have the 



38 STEAM POWER PLANTS. 

seam near the bridge wall back of that wall, thus making the front plate 
wider than the others. Ihe heads will be single riveted to the shell. 

Riveting and Holes for Rivets. — ihe holes tor rivets will be punched 
one-fourth inch small and drilled to size with ail plates and covering plates 
in place. The riveting is to be done by a hydraulic machine. As little 
hand riveting as possible is to be done. The plates are to be fitted metal 
to metal before riveting, brought up to butt in contact, and are to be prop- 
erly curved out to the ends. No filling pieces are to be used and no drift- 
ing is to be done. 

Caulking. — Caulking is to be done with a round nose tool. 

Tubes. — The tubes are to be of lap welded steel, and are to be beaded 
over the ends. A Prosser expander is to be used. The tube holes are to 
be rounded on each side to 1/16 in. radius, and not beveled as is customary. 
The tubes are to be located as shown on the enclosed blue print. (Fig- 
ure 16.) 

Manholes and Handholes. — There are to be two manholes in each boiler, 
one on top and the other in the front head below the tubes. The manhole 
on top is to be at one end of the boiler just far enough from the head 
to enable a man to get in feet first in either direction. This is to have a 
pressed steel frame, plate and yoke. The frame is to amply make up the 
area of plate cut from the shell and is to be double riveted thereto. The 
manhole in the head is to be located as shown on the accompanying print, 
is to be pressed on the plate and to have a pressed steel plate and yoke. 
There will be a 4 inch x 6 inch handhole in the back head. 

Bracing. — Above the tubes there will be four longitudinal tie rods pass- 
ing through the heads and upset at the ends, having a nut outside and 
inside the plates. There will be four braces from the heads to the shell 
riveted to the latter some five or six feet from the heads. These braces 
will be pinned to horizontal stiffening angles riveted to the heads. There 
will also be horizontal stiffening angles riveted to the heads above and 
below the longitudinal tie rods. Below the tubes the heads will be stif- 
fened by several short diagonal braces riveted to heads and shell. 

Steam Nozzle. — There will be one 7-inch steam nozzle midway between 
the heads of each boiler. It will be a steel casting double riveted to the 
shell, and drilled for 1% inch bolts. 

Steam Box and Dry Pipe. — Bolted up against the underside of the steam 
nozzle, or screwed into it, there is to be a 5 x 5 x 7-inch tee. Into each 
5-inch branch there is to be a 5-inch wrought iron pipe, the lengths to be 
equal and determined by the distance from the steam nozzle to the man- 
hole nozzle. The top of the pipe is to be about one inch below the shell 
and each branch is to be perforated on top with twenty-five 1-inch holes. 
The outer ends of the pipes are to be capped and the pipes strapped up 
to the shell. There are to be two % inch drain holes in the bottom of the 
steam box. 

Safety Valve Nozzle. — There will be no safety valve nozzle. 

Feed Pipe Nozzle and Feed Pipe. — This will be on top of the boiler near 
the front head. The feed pipe will pass through it, branch to one side and 
pass to the other end of the boiler where it will discharge. The feed pipe 
will be 2-inch brass, iron size, and will be furnished with the boiler. 

Blozv-off Pipe. — This will be tapped into the bottom of the boiler, and 
will be 2 1/4 inches in diameter. 

Safety Plug. — This will be screwed into the back head in the customary 
position. A Lunkenheimer plug filled with pure Banca tin is to be used. 



STEAM POWER PLANTS. 39 

Smoke Box. — The smoke box will not be formed by the extension of 
the main shell but by bolting a % inch plate thereto, and having a smoke 
nozzle riveted to it. The size of the smoke nozzle will be 18 inches x 5 feet 
G inches. The smoke boxes will overhang. The smoke box head will be of 
cast iron secured to the shell air tight. The doors will likewise be of cast 
iron fitting against planed faces and having turned hinge pins and drilled 
holes. The doors are to be clamped to the head after locomotive practice. 

Damper. — A damper with two plates with a rod between them is to be 
provided with a weighted lever and chain for its control. 

Front. — The front is to be made of steel plate Vz inch thick. 

Grates. — These will be furnished by the purchaser. 

Fire and Other Doors. — Each boiler will have two large size fire doors, 
with door frames, planed to match each other, and to have turned pins 
and drilled holes. The back cleaning door is to be clamped to the frame, 
after locomotive practice, to have planed joints, turned pins and drilled 
holes for pins. It will be so made that it can be securely built in. 

Supports. — The boilers will have a double set of supporting brackets at 
each end, eight for each boiler, the back ones having rolls. 

Fittings. — The contractor will furnish, but not attach, the following 
fittings for each boiler : 

One 10-incli company's steam gauge graduated to 300 pounds, 

and numbered every 20 pounds. 

One 5-inch company's safety valve set to blow at 127 pounds. 

One Reliance water column without safety device, and provided with 
two water glass fixture bosses on opposite sides at such distances apart 
as will accommodate an 8-inch exposed length of glass. There will be 
no gauge cock bosses. 

Two company's heavy pattern water glass fixtures with best 

Scotch glasses, 8-inch exposed length. 

Four extra glasses of proper length. 

Extra strong iron size brass piping for water column, all cut to length 
and threaded, and holes drilled and tapped therefor in shell. 

No gauge cocks will be used. 

Arch Bars. — Proper arch bars are to be supplied with each boiler. 

Buck Stays and Rods. — These are to be furnished and the buck stays are 
to be of 8-inch I-beams. 

Drawing. — The party receiving the contract is to furnish a first-class 
drawing of the boiler as built, and of the setting therefor. 

Testing. — Each boiler will be tested at the works of the contractor to 
190 pounds per square inch with water pressure and made tight under that 
pressure in the presence of a representative of Dean & Main. 

Inspection. — The boilers will be built under the inspection of Dean & 
Main and the Mutual Boiler Insurance Company. 

Reservation. — The right is reserved to reject any or all bids. 

Terms of Payment.— Fropos2i\s are to state the desired terms of pay- 
ment. 

Delivery.— The proposal is to state the guaranteed time of delivery of 
the three boilers. 

Specifications for water tube boilers. — An engineer's specifica- 
tion for water tube boilers can only be a very general statement 
of what is wanted, for the reason that such boilers vary greatly 



40 



STEAM POWER PLANTS. 



in design. The engineer can, however, describe what he wants 
and ask each bidder to supply information enabling him to under- 
stand thoroughly what each bidder proposes to furnish. The 
engineer should state in his specification the number of boilers 
he wishes to purchase, the amount of heating and grate surface 
each is to contain, the location of the plant for which they are 
wanted and the name of the owner or owners of the plant. If 
the boilers are to be erected and placed in lunning order by the 




Figure 17. — Boiler Room Plymouth Cordage Company, 



builder, it should be so stated. The engineer should state the kind 
of coal to be burned, the kind of service to be required of the 
boilers and the dimensions of the chimney and flues. It is well 
to furnish a sketch showing the location of the boilers, flues and 
chimney. If a mechanical stoker is to be used the boilermaker 
should be asked to furnish a boiler setting to suit. The engineer 
should require each bidder to furnish detail drawings showing 
all parts of the boiler and setting, in such a way as to show the 



STEAM POWER PLANTS. 41 

facilities for cleaning and inspecting the parts and the manner 
of making renewals. He should ask for the physical qualities of 
the metals used; the material of which the tubes are made; the 
name of the manufacturer of the different fittings used, such as 
the safety valve, blow-off cocks, water and steam gauges ; the 
character of feed piping, whether iron or brass. 

For certain types of water-tube boilers with straight tubes 
slightly inclined from the horizontal and connecting with vertical 
or nearly vertical headers at the front and rear of the boilers, the 
headers connecting with combined steam and water drums, there 
are usually several different arrangements of tubes that will meet 
a specification calling for a certain heating surface. For instance, 
there may be sixty 1 8- foot tubes so arranged that there are ten 
tubes in width and six tubes in height or there may be twelve 
tubes wide and five tubes high. The latter arrangement would 
mean a wider boiler costing more, but giving a wider and conse- 
quently larger grate that might be needed with low-grade fuels. 
It is probable, the heating and grate surface and coal burned be- 
ing the same, that a high narrow boiler of this type will give a 
better efficiency than a low wide one. If the boilermaker is to 
supply and erect the breechings, smoke flues, chimney dampers 
and damper regulator it should be stated in the specifications. If 
the engineer proportions the boiler it is hardly fair to exact a 
guarantee from the maker as to the efficiency of the boiler. He 
should, however, guarantee that the boiler will operate at 50 per 
cent, over its rated capacity without showing signs of deprecia- 
tion. 



Chapter IV. — The Selection of the Types of Engines, 
Dimensions of Cylinders, Speed, Steam Pressure, Etc. 

The method of buying a steam engine most frequently employed 
by engineers is to invite bids from a number of builders upon an 
engine which, with a certain number of revolutions, steam press- 
ure and back pressure, w411 develop a given horse-power. The 
cylinder dimensions are usually supposed to be looked after suffi- 
ciently when the bidders are asked to state the steam consumption 
they will guarantee. On opening the bids thus obtained, it is 
sometimes found that some offer engines with smaller cylinders 
than others, to do the same work. The prices are naturally 
different, and it occasionally happens that the purchaser does not 
get the engine best suited to his needs, first cost and economy of 
operation both being considered. The non-technical factory man- 
ager, knowing nothing of engines, frequently makes a mistake in 
this matter of purchasing an engine, as he does not know the type 
of engine he wants and much less w^hat its details should be. 
He, therefore, frequently buys something very different from what 
he needs. Such an individual should either engage a competent 
consulting engineer to invite bids for him on the type of engine 
best suited to the conditions, or go to one reputable engine builder. 
inform him of the conditions that exist, and have an engine built 
to suit them. There is no doubt but that there are builders fully 
competent to study the conditions involved and advise an owner 
what is required. Two or more builders should not, however, 
be placed in competition where the cheapest bid is likely to be 
the deciding factor in the selection of an engine, and an incom- 
petent person is to be the judge of the propositions offered. It 
could hardly be possible to educate the non-technical purchaser of 
engines, but there are a number of engineers who are not steam 
engineering experts that have to buy engines without the aid of 
expert advice; and it is hoped to give some general information 
and data to assist such in determining the type of engine, approxi- 
mate cylinder dimensions, etc., best suited for different situations, 



STEAM POWER PLANTS. 43 

so that bids can be invited upon a specific machine and thus 
secure the benefit of a competition, where all bids are made upon 
the sam.e basis. In doing this, the selection of the type of engine 
will first be discussed ; afterward, the determination of those fac- 
tors that fix the capacity and efficiency of an engine ; and finally, 
the method of applying these factors in the general equation for 
determining the power of an engine so that the cylinder sizes or 
volumes may be calculated. 

Selection of type. — To most people it is manifest that it would 
be bad engineering to install a costly triple-expansion engine that 
operates with the highest economy in a plant where fuel is of 
little or no value. Many situations, however, require the keenest 
judgment to select the type of engine best adapted for the service 
the engine is to perform. There is a saying that any expenditure 
for plant is warranted that results in savings which more than pay 
the interest on the expenditure, the depreciation and the cost of 
repairs on the plant. This is a simple proposition in itself, but 
it is not always easy to predict the saving that will follow the 
installation of a machine, or what the depreciation and repairs 
will be. As a basis for such calculations regarding steam engines, 
Table I is given, and in it is shown the steam consumption per 

TABLE I.— STEAM CONSUMPTION OF DIFFERENT TYPES OF ENGINES. 

Pounds of Steam 

Type of engine. steam per pressure, lbs. 

H.-P. per hr. gauge. 

High-speed simple 32 80-100 

High-speed compound non-condensing 24-26 150-110 

High-speed compound condensing 19-21 150-110 

Corliss simple non-condensing 26 80-100 

Corliss simple condensing 21 80-100 

Corliss compound non-condensing 20-22 150-110 

Corliss compound condensing 14-15 150-125 

Triple-expansion condensing 13 150- 

horse-power per hour which might be expected from various types 
of engines with different steam pressures. The figures given are 
believed to be fairly accurate in a relative sense and are supposed 
to represent about what would be obtained with each engine 
running at its most economical load with valves and pistons in 
good but not the best condition. In the figures given for con- 
densing engines, the steam used by the air pump is included. To 
arrive at the actual cost of power, the fuel cost and the cost 
of repairs, interest, depreciation, etc., should be taken into account. 
It can be safely assumed that with good anthracite or semi-bitu- 



44 STEAM POWER PLANTS. 

minous coal a boiler will evaporate 8 pounds of water per pound 
of coal ; hence the annual fuel cost of an engine will be : 
Annual fuel cost -= P X H. P. X h X c -^ (8 X 2,240), 
in which, 

P = the pounds of steam used by the engine per horse-power 
per hour. 
H. P. •== the average horse-power developed. 

h '= the number of hours during the year the power is being 
used. 

c = the cost of coal in dollars per ton of 2,240 pounds. 
To the annual fuel cost thus obtained, there should be added, 
say 4 per cent, of the cost of the engine to cover the interest on 
the investment and 8 per cent, for repairs, depreciation, etc. It 
is assumed that when the formula is used to compare condensing 
engines with simple engines that the boiler feed water in the case 
of the condensing plant is first warmed by the exhaust steam 
from the engine and afterward by the steam from the auxiliaries, 
so that there will not be enough difference in the temperature of 
the feed water in the two cases to warrant taking this difference 
into account. 

No really reliable figures as to the cost of engines can be given, as 
this is constantly varying due to the condition of supply and de- 
mand and the cost of materials. If an engineer is in doubt as to the 
type of engine needed for a special situation, bids on the types that 
are to be considered should be obtained, and from the prices thus 
obtained a decision can be made. The increased cost of the most 
economical engines is partly offset by the fact that not so great a 
capacity in boilers is required to run them, hence the cost of the 
boilers should usually be considered. Generally speaking, it has 
been found that the greater expense of economically working 
engines is more than offset by the gain resulting from their use. 
For all steam pressure over 100 pounds, with engines over 150 
horse-power, the compound engine in most situations, whether it 
is to be operated condensing or non-condensing, will save enough 
in fuel cost to pay for its increased first cost and cost of attend- 
ance, repairs, etc. There are situations where this statement would 
not be true ; for instance when the fuel cost is exceptionally low 
or when the demand for exhaust steam for heating or for manu- 
facturing purposes is in excess of the steam exhausted by the 
engines. It would then, it is manifest, be poor policy to buy an 



^BoHhm of Raof Truss 




STEAM POWER PLANTS. 45 

expensive engine for the sake of getting an economical one, when 
the economical use of steam in the engine is no object. Again, 
if an engine is only to be run occasionally, as in the case of a relay 
engine to a water wheel, the engine should not be as costly a one 
as if it were to run more frequently. In the latter case, the interest 
on the increased cost of an economical engine over one using 
more fuel might be more than the difference in the fuel cost, owing 
to the short time that the engine is used. Generally speakings 
triple-expansion engines for mill or electric work with steam 
pressures as low as 150 pounds have not shown that the saving 
due to their use is sufficient to pay for their increased cost over 
a compound engine. Engines used in the power plants of very 
large buildings, should, generally speaking, be of the compound 
type, if over 200 horse-power. They are naturally run non- 
condensing. Another point to be considered is the increased cost 
of attendants for the most economical engines over those with 
simpler parts and using more fuel. 

Steam pressure. — The steam pressure employed in simple 
engines may be said, generally speaking, to vary from 80 to 120 
pounds above the atmosphere and in compounds from 100 to 150 
pounds, although the latter are sometimes run wit'i lower press- 
ures than 100 pounds. The tendency is toward the hi?;her pressures. 
High-pressure steam especially in compound engines, is conducive 
to high economy, but it should not be forgotten that high steam 
pressures, and by that is meant pressures of 135 pounds and over, 
mean increased wear on the system, much trouble with steam 
piping if unusual care is not taken in constructing it, and an 
increased loss from leakage and condensation ; but for all these 
objections the higher economy of engines with high steam press- 
ures will more than compensate for the drawbacks if the plant 
is well designed and is placed in competent hands. In electric 
power stations and with mill and factory engines of large power, 
the pressure can well be from 135 to 150 pounds. In the latest 
large electric stations even higher steam pressures are used. 
High-pressure steam is of special importance where compound 
non-condensing engines are used. For plants for very large build- 
ings employing competent engine attendants, a pressure of at 
least 120 pounds should be selected if this type of engine is Xo 
be used ; and in large mills or large electric plants, v^hcrc the 
steam plants will be in competent hands, the steam pressure with 



46 STEAM POWER PLANTS. 

non-condensing compound engines should be as high as 150 
pounds. Even with pressures as high as 125 pounds the steam 
piping should have unusual attention both in the design and 
erection. 

Rotative speed. — The number of revolutions an engine is to 
run is frequently fixed by the fact that it is to be directly con- 
nected to a dynamo which has to be run at a certain speed, or 
by some other condition. The rotative speed is limited by the 
centrifugal force developed in fly wheels when in motion, by the 
maximum speed at which the piston should be run and, in the 
case of engines with a releasing valve gear, such as the Corliss, 
by the tendency of the valve gear to become noisy and give 
trouble at too high a speed. High-speed engines of lo-inch 
stroke with automatic cut-off controlled by a shaft governor, are 
usually run at about 325 revolutions per minute, and the rotary 
speed is decreased to about 150 revolutions in engines of 24 
inches stroke. An engine may be run at much lower rotative 
speeds than those mentioned, but it would then, of course, 
require a proportionally larger cylinder to develop the same 
power, other conditions being equal. With releasing gear engines 
with ordinary air dash-pots, the highest rotative speed that should 
be employed seems to be about 90 revolutions per minute. 
Eighty revolutions is better practice. In electric work the rota- 
tive speed is sometimes increased above 90 revolutions per minute 
for engines directly connected to a dynamo, but unless some 
special valve gear is used, permitting high speeds, the life of the 
engine is shortened and it is apt to be noisy and require con- 
siderable attention. The rotative speed of an engine is frequently 
limited by the proper speed at which the piston should be run. 

Piston speed. — Piston speed is usually defined as being the 
number of feet that the piston of an engine travels in a minute's 
time. It is obtained by multiplying the length of the stroke in 
feet by twice the number of revolutions per minute. Good prac- 
tice with high-speed engines limits the piston speed of small 
engines with a length of stroke of 12 inches at about 550 feet 
per minute and with engines of the 2-feet stroke at about 600 
feet. In larger engines 700 feet per minute is allowable, and 
in electric service this figure is sometimes exceeded in long 
stroke engines to obtain a high rotative speed. It is not well 
to go above 800 feet, however, for, when this piston speed is 



STEAM POWER PLANTS. 



47 




I 



-^^^^P 



W4^ 



^1 












W 



w 




Figure 18.— Power Plant, Lancaster Mills, Clinton, Mass. 

LOCKWOOn, GREENE & CO.. ENGINEERS. 



48 STEAM POWER PLANTS. 

exceeded, very large ports are necessary to admit the larger 
amount of steam required with high-piston speeds, and these 
large ports increase the clearance of the engine and make it less 
economical in the use of steam. 

Mean effective pressure. — When steam is admitted to a cylin- 
der during a portion of the stroke of an engine and then further 
supply is ''cut-off," the steam, after "cut-oft"" occurs, begins to 
expand as the piston advances and consequently the pressure 
falls. The work done in the cylinder is proportional to the aver- 
age effective pressure throughout the stroke, hence it is necessary 
in proportioning cylinders to know^ what this average or mean 
eft'ective pressure should be with different steam pressures. The 
mean effective pressure is one of the factors in the general equa- 
tion for determining the horse-power developed by an engine. Its 
selection is an important matter, for on it, more, perhaps, than 
anything else, the economy of the engine is dependent. Theo- 
retically the greatest amount of work is obtained from steam when 
it is admitted to a cylinder up to such a point in the stroke that 
it will afterward expand to the pressure that the engine is exhaust- 
ing against. Practically, it is not w^ell to have so complete an 
expansion. The more complete the expansion is (that is, the 
number of times the volume of steam at cut-off is expanded), 
the less the mean forward pressure must be, hence engines operat- 
ing with high economy work, up to a certain limit, with a lower 
mean eft'ective pressure than a similar engine working with a 
poorer economy. The lower the mean effective pressure is, how- 
ever, the larger the cylinder must be to accomplish the same 
work, hence the expansion may be so great and the mean effective 
pressure so small that the saving in fuel due to this complete 
expansion may not pay for the increased cost of the large cylin- 
der. This is, in brief, the commercial problem involved in the 
selection of cylinder sizes. 

Mean effective pressures for simple engines. — In Table II 
there are given the approximate mean effective pressures that are 
usually obtained with various steam pressures with CorHss and 

TABLE IT. — MEAN EFFECTIVE PRESSURES FOR DIFFERENT STEAM 
PRESSURES, IN POUNDS PER SQUARE INCH, FOR ENGINES OF THE 
SIMPLE TYPE. 

Steam pressure, gaugo 80 90 100 

Corliss.* condensing 26 28 30 

Corliss.* non-condensing 36 38 4(1 

Single valve, non-condensing 42 46 oO 

♦These data can be applied to four-valve, modei-ate or slow-speed engines. 



STEAM POWER PLANTS. 49 

other four-valve slow or medium-speed engines, condensing and 
non-condensing, when the minimum amount of steam per horse- 
power per hour is consumed. The table also shows the same 
data for simple single-valve engines of the high-speed type. 
The overload capacities of engines proportioned in accordance with 
the figures gi^^en in the table are described in a later paragraph. 

Proportioning cylinders of single-cylinder Corliss engines. — 
The first thing to do in determining the size of cylinder for an 
engine to develop a given horse-power is to fix the steam press- 
ure and afterward select a mean effective pressure proper for the 
conditions under which the engine is to work. Having the above 
data, the method of determining the cylinder size will be explained, 
in one case where the number of revolutions is fixed and in another 
case where it is not. It will first be supposed that the number 
of revolutions have been fixed. 

The general equation by which the horse-power of an engine 
is determined is in the form : 

H. P. = PXlXaXn-- 16,500 (2) 

in which 

P r= the mean effective pressure in pounds per square inch. 

1 =z the length of stroke in feet. 

a -= the mean area of the piston in square inches. 

n •= the number of revolutions per minute. 

In equation (2) the terms H.-P. (the number of horse-power 
to be developed), P and n are assumed to be known, and trans- 
posing we have : 

1 X a = H.-P. X 16,500 -- (P X n) (3) 

Substituting the value of P, n and H.-P., we can find the 
numerical value of 1 X a. Both of these quantities are to be 
determined. Table III shows in columns i and 2 the diameter 
and length in inches of cylinders for Corliss engines for which 
practically all large engine builders carry patterns. The cylinder 
sizes given are taken from the catalogue of the Allis-Chalmers 
Company. Column 3 shows the number of revolutions at which 
it is recommended these engines should run. Column 4 shows 
the product of the cylinder area in square inches by the length of 
stroke in feet for each cylinder, and column 5 shows the quan- 
tities given in column 4 multiplied by the number of revolutions 
given in column 3. Going back to the calculations, the numerical 
value of 1 X a, it will be remembered, has been found. We 



50 



STEAM POWER PLANTS. 



now look down column 4 until we find a number nearest to the 
numerical value of 1 X a. Opposite the number thus found are 
the dimensions of the cylinder that is seemingly required. One 
more • operation remains. The length of stroke of this cylinder 
in feet should be multiplied by twice the numxber of revolutions 



TABLE 


III.— DIMENSIONS 


OF CYLINDERS 
ENGINES. 


3 AND SPE 
Area cyl., sq. 


Dia. 






in. X stroke 


Cyl., 


Length 


Revs, per 


in ft. -= 


in. 


stroke, in. 


min. 


1 Xa. 


12 


30 


90 


282 


12 


36 


85 


339 


14 


36 


.85 


461 


14 


42 


82 


538 


16 


36 


82 


603 


16 


42 


78 


703 


18 


36 


80 


763 


18 


42 


78 


890 


18 


48 


75 


1,017 


20 


42 


75 


1,099 


20 


48 


72 


1,256 « 


20 


60 


75 


1,570 


22 


42 


75 


1,330 


22 


48 


72 


1,520 


2'^ 


60 


65 


1.900 


24 


48 


70 


1.809 


24 


60 


65 


2,261 


26 


48 


70 


2,123 


26 


60 


65 


2,654 


28 


48 


68 


2,463 


28 


60 


65 


3,078 


30 


48 


68 


2,827 


30 


60 


62 


3,534 


30 


72 


55 


4,241 


32 


48 


65 


3,217 


32 


60 


62 


4,021 


32 


72 


55 


4,825 


34 


48 


65 


3,631 


34 


60 


62 


4,539 


34 


72 


55 


5,447 


36 


48 


72 


4,071 


36 


60 


62 


5,089 


36 


72 


55 


6.107 


38 


60 


60 


5,670 


40 


48 


70 


5,026 


40 


60 


62 


6.283 


40 


72 


55 


7,539 


40 


84 


50 


8.796 


42 


48 


70 


5.541 


42 


60 


62 


6.927 


42 


72 


55 


8,312 


44 


48 


70 


6.082 


44 


60 


62 


7.602 


44 


72 


55 


9.123 


46 


60 


62 


8.309 


46 


72 


55 


9,971 


48 


60 


62 


9.047 


48 


72 


55 


10,857 



OF CORLISS 

Area cyl., 

sq. in. X 

stroke, it. X 

revs. = 

1 X a X n. 

25,447 

28.840 

39,252 

44,177 

49.461 

54,889 

61.070 

69,467 

76.338 

82,467 

90.478 

117.810 

99,784 

109,477 

123.542 

126.669 

147.026 

148.660 

172.552 

167,484 

200.118 

192.265 

219.126 

233.263 

209.105 

249.317 

265.402 

236.058 

281.455 

299.613 

293.146 

315,539 

335.897 

340,233 

351.859 

389.558 

414.691 

439,824 

387.923 

429.486 

457.195 

425.748 

471.364 

501.774 

515.189 

548.427 

560.963 

597.154 



that the engine is to run to obtain the piston speed; and if this 
exceeds good practice, as described in an earlier paragraph, a 
cylinder with a shorter stroke and larger diameter, but of 
approximately the same volume, can probably be found in the 
table, which will give the power without too great a piston speed. 



I 



STEAM POWER PLANTS. 51 

If the revolutions are fixed in the first place, the problem is 
simpler. We then can transpose equation (2) to: 

1 X a X n = H.-P. X 16,500 -- P (4) 

and after obtaining the numerical value of 1 X a X n, the proper 
diameter and stroke of cylinder and rotative speed of the engine 
required can be found opposite the number in column 5 of the 
table nearest to the numerical value of 1 X a X n. If there is 
not a close agreement between one of the numbers in column 5 
and the value of 1 X a X n, the revolutions may be increased or 
decreased as the former is respectively greater or less than the 
latter. 

It was explained that Table III gives the cylinder sizes of 
Corliss engines made by one company and that many builders 
carry patterns for these sizes. Most builders have additional 

TABLE IV.— DIMENSIONS OF CYLINDERS AND SPEED FOR HIGH-SPEED 
AUTOMATIC CUT-OFF ENGINES, 



Dia. 






cyl., 


Length 


Revs, per 


in. 


stroke, in. 


min. 


9 


10 


325 


10 


10 


325 


11 


10 


325 


11 


12 


300 


12 


12 


300 


13 


12 


300 


14 


12 


300 


14 


14 


275 


15 


14 


275 


16 


16 


250 


17 


16 


250 


18 


16 


250 


18 


18 


225 


20 


18 


225 


20 


20 


200 





Area cyl., 


Area cyl., 


sq. in. X 


sq. in. X 


stroke, ft. X 


stroke, ft. = 


revs. = 


IX a. 


1 X a X n. 


53 


17,225 


65 


21,125 . 


79 


25,675 


95 


28,500 


113 


33,900 


132 


39,600 


153 


45,900 


178 


48,950 


205 


56,375 


268 


67,000 


302 


75,500 


338 


84,500 


381 


85,725 


471 


105,975 


523 


104,600 



patterns varying more or less in size from those given, and it 
may be for a particular case a builder might furnish a cylinder 
with slightly shorter stroke, and correspondingly greater area of 
piston, so that the cylinder volume would be the same. Such a 
cylinder would give the same power and, because of the shorter 
stroke, the engine would be less expensive to build, the frame, 
guides and all reciprocating parts being shorter. For this reason 
it is not well for the engineer to be too rigid in fixing the cylinder 
dimensions. Cylinders of different engines to do the same work 
should have the same volume; but the stroke should not be 
shortened too much. 

Proportioning cylinders for single-cylinder high-speed engines. 
— Table IV contains the sizes of cylinders of a line of high-speed 



62 STEAM POWER PLANTS. 

automatic engines. Although no one builder carries patterns for 
them all, most builders have patterns for cylinders of approxi- 
mately the same volume as those given in the table. The engineer 
can determine the size cylinder required in the manner described 
for Corliss engines, using the mean effective pressure and 
rotative speed proper for this type of engine. A specification for 
this type of engine can name the length and diameter of cylinder 
wanted, but it should also state that bids upon engines of approxi- 
mately the same cylinder volume will be considered. It is, of 
course, unfair to handicap a builder not possessing patterns of 
exactly the dimensions desired by demanding that he make a 
pattern to conform exactly to the engineer's specification. 

Proportioning cylinders for medium-speed engines, — It is im- 
possible to give a table that is representative of the cylinder sizes 
of medium-speed engines, as those four-valve engines which run 
at higher rotative speed than Corliss engines and at lower rota- 
tive speed than the so-called high-speed engines are called. The 
reason for this is that no two builders have patterns for the 
same sizes of cylinders. It is, perhaps, just as well to select the 
engine size from the catalogue of one builder, using the same 
piston speed and mean effective pressure as for Corliss engines, 
and invite bids upon an engine with a cylinder or cylinders of 
equivalent volume. The shorter stroke should belong to the 
cheaper engine, other things being equal, for reasons explained 
above. An engine with too short a stroke in proportion to its 
diameter is not as economical usually, on account of greater 
clearances. 

Proportioning cylinders for compound engines, — The method of 
determining the size of cylinders of compound engines is some- 
what complicated by the fact that steam has to be expanded 
through two cylinders. Theoretically, the size of the high-press- 
ure cylinder for a given number of expansions in the engine has 
absolutely nothing to do with the capacity of the engine. In fact, 
a simple engine, with its single cylinder the same size as the low- 
pressure cylinder of a compound engine, would, theoretically, 
develop the same power as the compound if the cut-off in the 
single cylinder were adjusted so as to give the same number of 
expansions as exist in the compound engine. In practice, how- 
ever, the large number of expansions common in compound en- 
gines would not do in a simple engine, because of the excessive 



STEAM POWER PLANTS. 53 

■cylinder- condensation that would occur. Dividing the expan- 
sion between two cylinders, as is done in the compound engine, 
reduces the condensation, and that is why compound engines 
are used. For the purpose of determining the cylinder sizes of 
a compound engine it can be assumed that all of the work is 
done in the low-pressure cylinder and then determine its size by 
the formulas given for the simple engines, assuming a mean 
effective pressure that is proper for a compound engine. After 
the size of the low-pressure cylinder is determined, the high-press- 
ure cylinder dimensions can be found by selecting one whose vol- 
ume is in the same ratio to the volume of the low-pressure cylinder, 
that practice has found to be proper. 

Mean effective pressures for compound engines. — The mean 
effective pressures in compound engines are diiierent from those 
in simple engines for the reason that the steam pressures and 
ratios of expansion are higher. In Table V there are given 
values that can be assumed for the mean effective pressures for 

TABLE V. — MEAN EFFECTIVE PRESSURES FOR DIFFERENT STEAM 
PRESSURES, IN POUNDS PER SQUARE INCH, FOR COMPOUND EN- 
GINES. 

Steam pressure, gauge 100 125 150 

Corliss.* condensing 18 20 22 

Corliss,* non-condensing 20 31 33 

Single valve, high-speed, condensing 22 24 26 

Single valve, high-speed, non-condensing 32 34 36 

♦These data can be applied to four-valve, moderate or slow-speed engines. 

substitution in equations (3) and (4) to find the size of the low- 
pressure cylinder of compound engines of various types. The 
mean effective pressures given are equivalent to the mean effective 
pressures actually found in the low-pressure cylinder added to 
the mean effective pressure in the high-pressure cylinder multi- 
plied by the ratio of high-pressure to the low-pressure piston areas. 
The mean effective pressures given for compound engines are 
believed to be such as will ensure the lowest steam consumption 
per horse-power. Over load capacities are discussed later. 

The data given in the tables have been gathered mainly from 
an examination of a number of tests made by engineers known 
to obtain trustworthy results, where the conditions have been such 
as to obtain the highest efficiency. In all cases the mean effective 
pressure is based upon a back pressure of 16 pounds absolute in 
the case of non-condensing engines, and a vacuum equivalent to 
26 inches of mercurv in the case of condensing engines. After 



54 STEAM POWER PLANTS. 

the mean effective pressure is decided on, formula (3) should be 
used if the revolutions are not fixed, and formula (4) if they are 
determined upon, just as was done with simple engines, in calcu- 
lating the area and length of stroke of the low-pressure cylinder 
of a compound engine. 

After the size of the low-pressure cylinder is determined, the 
high pressure can be found by selecting one whose area is in the 
same ratio to the area of the low-pressure cylinder, as practice 
has found to be proper, as has been said. There is a difference 
of opinion among engineers as to the proper ratio of cylinder vol- 
umes with compound engines. Some engineers proportion the 
cylinders so that the amount of work done in each will be the 
same. This results, particularly with high pressures, in a con- 
siderably greater range of temperature in the high-pressure than 
in the low-pressure cylinder; and by many this is held to be bad 
practice, for it is well known that too great a temperature range 
results iri excessive cylinder condensation, and it is to overcome 
this enemy to high economy in the steam engine that compound- 
ing is resorted to. The general practice with Corliss condensing 
engines, running with constant loads, has been to use a ratio of 
I • 3> I • 3/^ ^^^ I • 4 with steam pressures of 125, 135 and 150 
pounds respectively. Recently the tendency of a few engineers 
and builders has been toward a comparatively larger low-pressure 
cylinder than is given. Mr. George I. Rockwood, M. Am. Soc. 
M. E., has persistently advocated a cylinder ratio as high as i 
to 7 for a steam pressure of 150 pounds, and the most economical 
compound engine ever tested, that at the Grosvenordale Mills, 
Grosvenordale, Conn., which gave a steam consumption under 
12 pounds per horse-power per hour, had a cylinder ratio of 
about that proportion. A number of other engines with similar 
cylinder ratios have shown almost as good an efficiency. With 
high-speed automatic single-valve engines the cylinder ratio 
varies from about i : 2^ with 100 pounds pressure to about 
1 : 3 with a pressure of 150 pounds. An advantage in having 
the high-pressure cylinder fairly large in comparison with the 
low-pressure is the greater capacity for overloads that the engine 
will then have. 

Engines with variable loads and overload capacities. — The 
mean effective pressures that are given for both simple and com- 
pound engines assume that the engines are to run with a steady 



1 



STEAM POWER PLANTS. 55 

load and that it is desirable that they should work with the 
highest economy. In other words, the mean effective pressures 
given are such as will secure the lowest steam consumption. The 
matter of maximum economy is often of less importance in an 
engine than its maximum capacity, to take care of overloads for 
short periods. All engines are able only to work at maximum 
economy at a certain load. As the load diminishes or increases, 
the steam consumed per horse-power developed becomes greater. 
With a variable load an engine has to be large enough to supply 
the maximum power required, but when the load varies it is, 
generally speaking, better to proportion the engine so that it will 
be operating at the highest economy when working against a load 



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Figure 19. 



PressurcG. 

-Economy Curve Simple Corliss Engine. 



that is something less than the maximum that it will be called 
upon to supply, for the reason that it will be working most of 
the time partly loaded, and it should be proportioned to meet this 
average load with the consumption of as little steam as possible. 
An engine should be of such a size that its most economical load, 
that is, the load under which it will operate with the least steam 
per horse-power, is equal to the average power required, provided 
the maximum power that it can develop is not less than the maxi- 
mum power that will be required. Hence, if an engine is to fur- 
nish power where the maximum demand is 400 horse-power and 
the average demand 300 horse-power, the engine required would 



56 STEAM POWER PEANTS. 

be one whose most economical load was 300 horse-power, and 
300 horse-power would be the quantity substituted in the general 
equations (3) or (4) for determining the cylinder sizes. 

For the purpose of showing the variation in steam consump- 
tion due to a variation in load, the results of a number of tests, 
believed to be reliable, made upon engines of various types, are 
shown in the accompanying diagrams. Figure 19 shows the 
result of a test by Mr. George H. Barrus upon a 16 x 42-inch 
simple non-condensing Harris-Corliss engine running 85 revo- 
lutions per minute with a steam pressure of 100 pounds. It will 
be noticed that the most economical rating on the basis of steam 
consumed per indicated horse-power per hour was when the mean 
effective pressure was about 40 pounds, increasing slightly at 47 
pounds, which was probably very near the maximum load of 
the engine. If, therefore, an engine is rated in accordance with 
the mean effective pressures given in Table II it is probable that 
the simple non-condensing Corliss engines, with a single eccentric 
driving both the steam inlet and the exhaust valves, would stand 
an overload of at least 25 per cent, and simple condensing Corliss 
engines over 50 per cent. 

A number of tests made upon simple high-speed engines, with 
single valves, running non-condensing, are reproduced in Figure 
20, and the curves there shown representing the steam consump- 
tion with the variation in the mean effective pressure are num- 
bered to correspond with the data in Table VI. Tests numbered 
I and 2 were made by Mr. J. M. Whitham and were printed in 
The Engineering Record of July 9, 1898. Test number 4 was 



TABLE 


VI.— DATA 


OF 


SIMPLE NON 


-CONDENSIN 


G HIGH-SPE 


]ED ENGINE 






TESTS SHOWN 


IN FIGURE 


20. 




No. 


Diam. 




Stroke Revolutions 


Steam 


Make of 


test. 


cylinder. 




cj'linder. 


per mm. 


pressure. 


engine. 


1 


13 




12 


280 


100 


Ames 


2 


8 




10 


350 


100 


Ames 


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13 




12 


250 


95 


Ames 


4 


12 




14 


245 


80 


McEwen 


5 


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12 


280 


95 


Ames 


6 


13 




12 


250 


95 


Ames 


7 


13 




12 


250 


95 


Ames 


8 


17 




16 


225 


100 


Ames 


9 


17 




16 


270 


100 


Ames 



made by Professor R. C. Carpenter and was taken from Paper 
DXXIII, Transactions American Society of Mechanical Engi- 
neers. The remaining tests were made by Air. E. J. Armstrong 
and were taken with his permission from, a paper read by hini 



STEAM POWER PLANTS. 



57 



before the Engine Builders' Association. Test number 2 was 
made upon a very small engine, but "he test was not carried far 
enough to give exact data as to the proper load for it. It is 
interesting as showing the influence of size upon the steam con- 
sumption. Curves 8 and 9 were obtained from an engine of the 
same make only considerably larger and show a better economy, 
due, doubtless, to the larger size of engine. Curve number 4 
shows the steam consumption of an engine with a boiler pressure 
of only 80 pounds above the atmosphere. The most economical 



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Mean 



Pressures. 



Figure 20. — Economy Curve Single Valve Simple Engines. 



mean effective pressure in the latter case appears to be a little 
less than half the boiler pressure. Most of the remaining curves 
show the steam consumption of engines operating under press- 
ures of from 95 to 100 pounds. The most economical result with 
a steam pressure of 95 to 100 pounds seems to be with a mean 
effective pressure of from 45 to 55 pounds. Generally speaking, 
therefore, with the mean effective pressures recommended in 
Table II, the curves, with the exception of those numbered 2, 8 



53 STEAM POWER PLANTS. 

and 9, which were not carried out to the maximum capacity of 
the engine, seem to indicate that overloads of about 33V3 P^^ 
cent, could be met without a reduction in the speed of the engine. 
Data upon single-valve high-speed engines running condensing 
were not obtainable, as they are not often used. 

Curves i and 2, Figure 21, shows the variation in economy of a 
9 and 16-inch by 15-inch McEwen compound single- valve engine 
operating under a steam pressure of 112 pounds, a vacuum of 22 
inches and a rotative speed of 265 revolutions per minute. One 
test was made with the cylinders steam jacketed and one with the 
jackets shut off. The tests were made by Prof. R. C. Carpenter 
and have been taken from Volume DXXIII, Transactions of the 
American Society of Mechanical Engineers. It is seldom that 
engines of this type are provided with steam jackets, as the gen- 
eral impression seems to be that the saving does not warrant the 
expense. It will be noticed from the un jacketed test that the most 
economical rating, with a steam pressure of about no pounds, 
seems to be with a mean effective pressure, referred to the low- 
pressure cylinder, of 26 pounds. Upon this basis it would seem 
that a compound condensing high-speed engine could easily run 
with an overload of over 50 per cent., particularly if the auto- 
matic cut-off be applied to both cylinders. 

Curve number 3 in Figure 21 shows the variation in economy in 
a 12 and 20-inch by 13-inch non-condensing engine, made by 
the Ball Engine Company and tested by Messrs. George H. 
Barrus and W. S. Monroe. The average boiler pressure was 
about 166 pounds, with practically no back pressure except that 
of the atmosphere. The rotative speed was about 175 revolutions 
per minute. The most economical mean effective pressure seems 
to be about 40 pounds compared with about 26 pounds for the 
un jacketed test of the McEwxn condensing engine. While there 
is considerable difference in the steam pressure used by the two 
engines, it will be noticed that, if the loads were the same, the 
non-condensing engine would require a smaller cylinder than the 
condensing engine, provided both were operating with the lowest 
possible steam consumption per unit of power developed. Had 
the Ball engine been rated on the basis of a mean effective press- 
ure of 40 pounds referred to the low-pressure cylinder, the over- 
load capacity would have been about 33^/3 per cent. The tests 
were not carried sufficiently far, however, to determine if the 



STEAM POWER PLANTS. 



59 



engine could be operated at greater load than that shown by 
the chart. 

The compound non-condensing Corliss engine rated upon the 
mean effective pressures given in Table V can easily stand 2^ 
per cent, overload if there is but a single eccentric driving the 
valve gear, and more than that if separate eccentrics are used 
to operate the steam and exhaust valves, for with two eccentrics 
a much later cut off in the cylinder can be secured than with 
one. With compound condensing Corliss engines rated upon the 
mean effective pressures given in Table V, overloads of at least 
50 per cent, with one eccentric and probably 75 per cent, with 
two eccentrics could be withstood without very greatly affecting 
the engine^s speed. 



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Wean Effed-iv© Pressures. 

Figure 21. — Economy Curve Single Valve Compound Engines. 



Superheated steam, steam jackets and reheaters. — Superheated 
steam, steam jackets enclosing the walls of steam cylinders and 
reheating receivers placed between the cylinders of multiple 
expansion engines are used to reduce cylinder condensation. The 
almost universal use of superheated steam on the continent of 
Europe in steam plants of recent construction and the remarkably 
high economy secured, gains from 10 to 20 per cent, over the use 
of saturated steam having been reported, has drawn the attention 
of American engineers to this practice so that the use of super- 
heated steam is increasing considerably in the United States. The 
practical objection to its use, heretofore, has been in the deteriora- 
tion of the superheating devices used and in the difficulty of lubri- 



60 STEAM POWER PLANTS. 

eating engines where the steam is highly superheated. Recently 
three or four makes of superheaters have been introduced in the 
United States, and their extensive use abroad has demonstrated 
their durability and efficiency. The use of poppet valves in steam 
engines has overcome the difficulty of lubrication, although for 
temperatures under 500 degrees Fahrenheit these are said to be 
unnecessary. Superheaters are of two types, those that are placed 
in the path of the gases in the boilers, or in the flue leading from 
the boiler to the chimney, and those that are heated by an inde- 
pendent furnace. 

Steam jackets are seldom used upon any engines but those of 
the slow and medium rotative speed types, and their use becomes 
of less value as the speed is increased. Except for slow moving 
pumping engines their value is still a matter of doubt, although 
some engine builders provide them. Reheating receivers are in 
more common use, but their value is also a matter of dispute. 
The heating is done by a coil filled with steam of a higher press- 
ure than that of the steam passing through the reheater. Com- 
pound and triple expansion engines of the slow and medium 
speed type are usually provided with them. 

Steam turbines. — These devices for generating power by means 
of the impact of a current of steam upon the turbine buckets have, 
some time since, gotten beyond the experimental stage in the 
United States and they have been in commercial use in Europe 
for a considerable period. They possess a number of points of 
superiority over reciprocating engines and among these is the 
small variation in the steam consumption per unit of power de- 
veloped that occurs with a change in the load, also, the fact that 
the bearings are the only rubbing surfaces hence the efficiency 
of the turbine is not impaired by use to the extent that it is with 
reciprocating engines. The economy of the steam turbine com- 
pares favorably with all but the most economical engines and the 
turbine is particularly adapted to use superheated steam, for with 
high superheating there can be none of the difficulty as regards 
lubrication that there is with some reciprocating engines. Dr. R. 
H. Thurston has called the steam turbine the engine of "maximum 
simplicity and highest thermal efficiency." 



Chapter V. — Specifications for Steam Engines. 



There is occasionally a tendency on the part of some to ridicule 
elaborate specifications for steam engines, yet as a specification 
is a description of what one party to a contract agrees to furnish 
to another, it should be sufficiently complete to define exactly 
what is to be supplied. A complete specification is unnecessary, 
perhaps, where an owner engages a builder, without competition, 
to construct and install an engine suited for existing conditions 
and agrees to pay for whatever the builder elects to supply. In 
competitive bidding, the builder is not legally bound to supply 
anything more than that which the specification calls for, and all 
bidders are not apt to figure on doing more than that in prepar- 
ing their bids, knowmg full well that other bidders will not do 
so. Hence, if it is found, after a contract is made, that there are 
some desirable details which have been overlooked by the en- 
gineer in his specification, they must be purchased and paid for 
as extras, at, naturally, a higher figure than what they would 
cost if specified in the beginning. 

The amount of detail necessary in a specification naturally 
varies with the size of the engine to be purchased, and the extent 
to which the design departs from the standard types for the serv- 
ice. It is the author's intention to call attention to a number of 
details which must be considered in buying a large engine, al- 
though reference to them may be omitted in a specification for 
less important work. Many engineers believe in specifying the 
cylinder dimensions, at least in a general way, so that all bidders 
may bid upon engines of equal capacity. Methods of determin- 
ing these dimensions for simple and compound engines of various 
types were given in the preceding chapter. While they may be 
fixed by the engineer, some latitude should be given bidders in 
order that standard patterns may be utilized. 

A specification usually begins by stating the type of engine or 
engines wanted, whether it is to be of the simple, compound, or 
triple-expansion type, whether it is to be run condensing or non- 



62 STEAM POWER PLANTS. 

<:ondensing, and where it is to be located. Even though the en- 
gineer fixes those dimensions that determine the capacity of the 
engine, the specification should state the load at which the engine 
is to operate with the highest economy, the maximum load that it 
is to be called upon to operate, and the kind of service to which 
it is to be subjected. If guarantees as to capacity and efficiency 
are to be required from the builder, these data are, of course, 
essential. Even if they are not, and the engineer assumes the 
responsibility for the fulfillment, by the engine, of the require- 
ments imposed by existing conditions, as he does when he fixes 
the cylinder dimensions, steam pressure and rotative speed, the 
>engine builder should be informed as to what will be required of 
the engine, as he is very apt to make calculations that will serve 
as a check on those of the engineer. 

Sometimes a specification states that the price of the engine 
is to include its delivery and erection on a foundation supplied 
by the owner, and placing it in proper running condition. Again, 
however, the engine is sold free on board cars at the railway 
point nearest the locality where the engine is to be used. In the 
latter case the builder usually supplies a man to take charge of 
the erecting of the engine, which is done by labor employed by 
the owner under direction of the builder's erector. 

It is assumed that the engineer has determined the cylinder 
dimensions, the rotative speed, steam pressure, and whether the 
engine is to be run condensing or non-condensing; hence the 
specification should give : Diameter and stroke of cylinders ; 
number of revolutions per minute; horse-power to be developed 
when working at highest efficiency; horse-power at maximum 
load ; steam pressure ; back pressure if run non-condensing, or 
vacuum if run condensing. 

As before stated, an engineer should not be too rigid in regard 
to cylinder dimensions, and it is well, particularly when purchas- 
ing high-speed or medium-speed engines, to state in the specifica- 
tions that engines with cylinder volumes equivalent to those 
specified will be considered. There are objections to an engine 
with too short a stroke in proportion to the area of piston ; these 
were stated in the preceding chapter. If the engine is to be run 
condensing and the builder is to supply the condenser, provision 
should be made for it. 

The engineer should describe in a general way the kind of 




250 H.W. maty Converters. 
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Plate 6. — Power Station-. I'.vion Traction C\)mi>a.\-v, Axncr.io.v, In-d. 



STEAM POWER PLANTS. 63^ 

valve gear that is wanted. If the engine is to be of the compound 
Corliss type, the automatic cut-off might be applied to one or 
both cylinders. It is better to have it act on both cylinders if the 
load is variable, for the reason that a more equal distribution of 
the load between the cylinders will occur at light loads than there 
will if the cut-off is applied only to the high-pressure cylinder. 
Again, for Corliss engines, a separate wrist plate for the steam 
and exhaust valves, each driven by a separate eccentric, may be 
specified so that the engine may work with a later cut-off and con- 
sequently greater overload than is possible if both valves are 
driven from one eccentric. The cut-off may be applied to both 
cylinders in other types of compound engines. 

If the cylinders are to be steam jacketed in barrels or heads, 
or both, it should be so stated. Consulting engineers seldom pay 
much attention to this question, as the value of steam jackets is 
still a disputed point. Generally, engines for electric service and 
factory work are not steam- jacketed, particularly if the piston 
speed is over 600 feet per minute. It is the custom in multi- 
cylinder engines of the medium-speed and slow-speed types, tO' 
place reheating receivers in the steam pipes betv/een the cylinders, 
in which the steam is heated in transit from one cylinder to the 
other by live steam admitted to a coil of pipe. The value of these 
reheaters is also a matter of dispute. However, if they are 
wanted, they should be specified, also the manner in which the 
condensation that occurs in them is to be disposed of. The steam' 
passing through the heater from one cylinder to the other is 
usually at a much lower pressure than the steam, in the coils, 
hence the condensation must be drawn off by separate traps. The 
connection of these traps with the reheater and with a receptacle 
into which they can discharge, should be made either by the en- 
gine builder or the steam piping contractor. 

If the engine is to be of the Corliss type, the kind of bed that 
is wanted should be mentioned. Two forms are made by most 
builders, one, known as the heavy-duty type, is adapted for heavy 
work and high pressures, and the other, the girder frame, is 
lighter and is of older design. The heavy-duty design is almost 
invariably used for pressures over 125 pounds and to an increas- 
ing extent in lower pressures ; being much stronger, it is a little 
more expensive. If bids are called for a high rotative-speod auto- 
matic engine, the specifications should call for an iron sub-base 



64 STEAM POWER PLANTS. 

with the engine, for all builders do not furnish them except at 
extra expense. Occasionally the iron sub-base is not used and 
the bed of the engine is bolted to a brick foundation which is built 
up above the floor the height of the sub-base. 

There are a number of points concerning the design of the en- 
gine, chiefly relating to dimensions of wearing surfaces and the 
strength of parts, that engineers rarely fix. It is the custom of 
some, though, to ask each builder what he intends to furnish in 
respect to certain details, usually about as follows : Diameter 
and length of bearings, diameter and length of cross-head pins, 
diameter and length of crank pins, diameter of shaft in the body, 
dimensions of cross-head shoes, length of connecting rod, diam- 
eter and face of fly wheel (both may be fixed by the engineer), 
weight of fly wheel, weight of engine bed, weight of entire en- 
gine. 

When these data are received from each builder the engineer 
can tabulate them and compare the proportions of the engines 
offered. If any part of an engine differs from that of others 
enough to warrant such a course, the engineer can ask the reason 
for this deviation, and if it is not a good one the builder can be 
requested to modify his design, or the bid can be rejected. The 
engine builder should be asked to furnish a blue print or draw- 
ing of some kind showing a plan and elevation and the principal 
dimensions of the engine he proposes to furnish. 

Regarding details of construction of engines, most American 
engines are built after standard designs adopted by each builder 
and not much attention is usually paid in specifications to these 
details when builders of established reputation are bidding. 
Most builders furnish catalogues containing illustrations of the 
details of various parts of their engines, such as the valves, valve 
gear, governor, piston, main bearings, crosshead, etc. If an 
engineer is obtaining bids on an engine the details of which are 
unknown to him such illustrations can be asked for, When about 
to execute a contract with a builder, it can be stated in the con- 
tract that the details of construction are to correspond in design 
with drawings or blue prints or catalogue sketches furnished by 
the builder. 

There are a great many minor details of an engine, such as oil 
-cups, sight-feed lubricators, throttle valve, relief valves on the 
cylinders to prevent them from being damaged by water, cylinder 



STEAM POWER PLANTS. 65 

lagging, steam and vacuum gauges, gauge board, provision for 
attaching the indicators to the cylinders, etc., that have to be 
looked after, and many builders furnish a printed specification 
which refers in more or less detail to some of these matters. This 
specification can be asked for and made part of the contract, but 
before so doing care should be taken that it does not conflict with 
the specification issued by the engineer. 

The character of materials used in engine construction is not 
usually given much attention in an engineer's specification, but 
recently the materials of which shafts of large engines are made 
is receiving more thought, and the kind of metal used, and its 
treatment, is frequently specified. The most advanced practice 
is found, probably, in the fluid-compressed hollow-forged treat- 
ment, perfected by the Bethlehem Steel Company. The molten 
steel is poured into a cylindrical mold and subjected to an enorm- 
ous pressure while cooling, so as to diminish the blow holes that 
frequently occur in the ordinary method of casting. The ingot 
is cooled slowly and the impurities usually collect at its axis ; after 
it has cooled, an axial hole is bored through it to remove these 
impurities. The ingot is then reheated and a mandrel is slipped 
through this hole, after which it is forged under a slow-moving 
hydraulic press, the action of which penetrates much more deeply 
into the metal than is the case with the blow of a steam hammer. 
After forging, the ingot is annealed to remove internal strains 
and improve the structure of the metal, which is then machined 
to size. Sometimes the shaft is oil-tempered after annealing. 
Open-hearth and nickel steels are used, the small percentage of 
nickel added tending to raise the physical properties of the mix- 
ture. A large number of recent important engines for mili and 
electric power house service have been equipped with shafts made 
in this way. 

The time of delivery of an engine should be given in a specifi- 
cation, and with large engines the builder is sometimes required 
to furnish a man to operate the engine for a short period after it 
is erected. If the engine room is to be fitted v/ith a traveling 
crane operated by electricity or by hand, it is well to notify the 
engine bidders to that effect, as the use of a crane reduces the 
cost of erecting engines and the owner should have the be iefit 
of this. 

In regard to steam piping, the engine builder usually supplies 



66 STEAM POWER PLANTS. 

and connects the piping between the cyhnders in a compound 
or triple-expansion engine. In large compound engines, particu- 
larly of the cross-compound type, that is with the cylinders placed 
side by side and driving separate cranks, it is frequently the cus- 
tom to place a valve in the pipe carrying the exhaust steam from 
the high-pressure to the low-pressure cylinder, and to run a 
branch from the high-pressure steam pipe to this exhaust pipe 
connecting with it at a point between the low-pressure cylinder 
and the valve mentioned. With this arrangement the high-pres- 
sure cylinder can be cut out, and the engine driven by the low- 
pressure side alone. The pipe conveying high-pressure steam 
to the low-pressure cylinder is usually provided with a pressure 
reducing valve as well as an ordinary stop valve. By connecting 
the exhaust from the high-pressure cylinder at a point between 
that cylinder and the stop valve between the two cylinders, with 
the main exhaust pipe, and by placing a valve in the exhaust from 
the low-pressure cylinder, the low-pressure cylinder can be en- 
tirely cut out and the engine driven by the high-pressure cylinder. 
The advantage of such an arrangement in the event of the break- 
down of one side of the engine is obvious. An arrangement of 
this kind is shown very nicely in Figure i8. 

For electric work, where revolving parts of dynamos are 
mounted on the engine shaft, as is the custom in directly con- 
nected work, the specifications should require the engine builder 
to cut a key-way in the shaft. The dynamo builder usually sup- 
plies a key for keying the armature of the dynamos on the engine 
shaft. The dynamo and engine are sometimes shipped by their 
respective builders to the site of the power plant and the engine 
or the dynamo builder fits the armature to the shaft. In other 
instances the armature of the dynamo is shipped to the engine 
builder and is put on the shaft by the latter. The specification 
should state what each builder is to do in this respect. 

A specification often asks what steam consumption the builder 
of an engine will guarantee. If a guarantee as to steam consump- 
tion is to be made, it should be of the following general form: 

"The engine is guaranteed to consume not more than 

pounds of steam per indicated horse-power per hour when de- 
veloping — — horse-power when running at a speed of 

revolutions per minute with a steam pressure of pounds 

above the atmosphere, and with a back pressure of pounds 




^liyecfion Pipe.- X J ,i 

Floor Siand. 





'J3ZIUIOU001 \ C 



:jJ0-^°l3 ■JSZ!UJoup:ij 






japM P^J UO 2AI0/\ JOJ. pUOiSJOOjJ 



•0A/Dyi uojpafui jo^ puofs javij 







Plate 7. — Piping in Station, Woburn Heat, Light and Power Company, Woburn, Mass. 



i 

i 



STEAM POWER PLANTS. 67 

above the atmosphere." The specification should state that in 
case of dispute the steam pressure is tO' be the average pressure 
as obtained by a throttled steam gauge connected to the steam 
pipe close to the throttle valve, or by means of a steam pipe dia- 
gram obtained by attaching an indicator to the location named. 
If the engine is to run condensing instead of with a back pressure 
above the atmosphere the vacuum to be carried should be stated. 
The usual vacuum is 26 inches of mercury. If the engine is pro- 
vided with steam jackets and reheating receivers, it should be 
stated that the steam used by them is to be included in the con- 
sumption of the engine. If the engine is to run condensing, the 
steam used by the air-pump should be included, provided the 
engine builder supplies and is thereby responsible for the effi- 
ciency of the condenser. Sometimes, when condensers are not 
supplied by the engine builder, the steam used by the air-pump 
is not considered as being part of the steam used by the engine. 
If the air-pump steam is or is not to be considered as part of the 
engine consumption, a statement to that effect should appear in 
the guarantee. It is usually the custom to measure the degree 
of vacuum obtained by a gauge attached to the exhaust pipe of 
the engine close to the engine and a specification should state 
that the vacuum is to be so measured. 

A fair guarantee to ask concerning the regulation is that the 
speed of the engine shall not vary more than i^^ per cent, above 
or below the normal speed under any condition of load. The 
builder should guarantee the workmanship and materials to be 
of the best, and agree to make good at his expense any defects 
in the engine, not due to neglect, that develop during the first six 
months or year it is in operation. 

The accompanying specification was prepared by Mr. Nicholas 
S. Hill, Jr., M. E., and it is printed here with his permission. It 
should be understood that it was drawn for the purpose of ob- 
taining a small automatic high-speed engine for a private cor- 
poration that obtained bids from several reliable builders whose 
engines were well known. Perhaps in public work where com- 
petition is open to all and where the lowest bid has to be accepted 
further detail would have been necessary. 



68 STEAM POWER PLANTS. 

SPECIFICATION FOR A 300 I. H. P. NON-CONDENSING 

ENGINE. 

In the following specification the noun "Company" is used to designate 
the purchaser, the (purchaser's name and address). The noun "Builder" 
is used to designate the seller, the contractor, the manufacturers of the 
engine. 

Rejection. — The Company reserves the right to reject any or all bids. 

Engineer. — The interpretation of the specifications hereinafter set forth 
shall be left to the Engineer appointed by the Company, and the inspec- 
tion of all materials furnished and all tests for the determination of the 
fulfillment of the guarantee herein contained shall be made under the di- 
rection of the said Engineer. 

Test. — The engine will be tested at suc'.i time, after the erection and 
completion of engine and generator, as the builders may select and after 
the Engineer shall have received at least one week's notice. The Com- 
pany will furnish the necessary fuel, oil and supplies and the contractor 
will be required to furnish the indicator rig and prepare the engine for 
test. The Engineer will furnish the indicators. A run of ten hours will 
be made and the load will be maintained as nearly as possible at 300 
I. H. P. The conditions of the test will be fixed at the time of the signing 
of the contract as agreed between the Engineer and the Builder, 

Kind of Service. — The engine is intended to operate a generator driving 
motor driven tools located in the shops of the Company. 

Location. — The engine is to be located on foundations in the power 
house of the (name) Company at (place). 

Type of Engine. — The engine desired is of the single valve, tandem com- 
pound, fly wheel governor, automatic cut-off type, with extension sub-base, 
direct connected to a (name) generator, size No. — , 200 K. W., 250 volt 
generator. 

Conditions of Erection. — The Builders will furnish and erect engine on 
foundation supplied by the Company. The engine may be unloaded di- 
rectly from car at the door of the power station within 15 feet of the 
foundation. The station is equipped with a traveling crane of five tons 
capacity. The armature for the generator will be placed on shaft at 
the power house. 

Conditions of Operation. — The engine is to run non-condensing at 200 
revolutions per minute. Steam pressure 125 lbs. above the atmosphere. 
Back pressure 15 lbs. absolute. The maximum load for which engine is 
intended equals 400 I. H. P. The engine is to operate at highest efficiency 
with load equal 300 I. H. P. The average load will equal 175-200 I. H. P. 

Size of Cylinders. — The cylinders shall be approximately 18 inches and 
291/2 in. x 18 in. or I8V2 in. and 30 in. x 17 in. 

The volumes of cylinders furnished shall be not less than the volumes 
herein specified and the ratio of the cylinder volumes shall be between 
2.6 and 2.8. 

Speed Regulation. — The speed regulation shall be within 1.5 per cent, 
above or below normal. 

Piston Speed. — The piston speed shall be not less than 560 feet per 
minute nor more than 600 feet. 

Clearance. — The clearance shall not exceed 8 per cent. 

Indicator Attachment. — Bra^s piping for indicator with three way valve 
is to be furnished for both high and low pressure cylinders. 




oect on through Boiler Room, 



Longi + ud incil Section 
Plate 8. — Power Plant, Massachusetts General Hospital, Boston, Mass. 



STEAM-POWER PLANTS. G9 

Dimensions and Weights. — The Builder shall furnish the following data 
in regard to engine : 

Total weight of engine. 

Total weight of heaviest part. 

Total weight of fly wheel. 

Diameter and -length of main bearings. 

Diameter and length of cross-head pins. 

Diameter and length of crank pins. 

Diameter of main shaft in body. 

Diameter and face of fly wheel. 

Length of connecting rod. 

Blue Prints, Template, Specifications. — The Builder shall furnish blue 
print of engine and foundations which shall form a part of these specifica- 
tions after acceptance of proposal. A foundation template and foundation 
bolts shall be furnished by the Builder. The foundation bolts to be pro- 
vided with washers at least 10 inches square and to be threaded for two 
nuts at top. The Builder shall also furnish spoclfication of the lubricators, 
oil cups, tools, etc., to be supplied with engine. 

Materials. — All materials used in the construction of the engine to be 
the best of their various kinds and to be in strict conformity with the latest 
modern practice. 

Guarantee.— The. engine shall be guaranteed to consume not more than 
24 lbs. of steam per I. H. P. per hour, when developing 300 H. P., when 
running at a speed of 200 revolutions per minute with a steam pressure 
of 125 lbs. above the atmosphere and with a back pressure of 15 lbs. ab- 
solute. 

The Builder shall also guarantee to make good any or all defects de- 
veloped, within 150 days from the time of starting engine, which may be 
due to inherent defects in materials or faulty workmanship and design, 
provided such defects are developed when engine is running at less than 
50 per cent, overload. 

Painting. — All unfinished iron work about engine shall be filled, rubbed 
smooth and receive one coat of paint before leaving shop. A second coat 
is to be applied after erection and finally a finish coat highly enameled. 
The color is to conform with machinery already in place in the engine 
room. Quality of paint to be such as to insure against blistering, peeling 
off or fading and shall be satisfactory to the Engineer. 

Covers. — The engine is to be supplied with a neatly fitting and well 
made oiled canvas cover to be approved by the Engineer. 

Time of Delivery. — The Builder shall specify the earliest possible date 
of delivery. 

Price. — The price submitted by the builder shall include delivery and 
erection in conformity with the preceding specification. 



Chapter VL — Steam and Water Piping. 

Drawings. — After contracts have been let for the engines, boil- 
ers, pumps, feed-water heater and other auxiliaries of a plant, the 
engineer should obtain accurate drawings or blue prints of each, 
showing in plan and elevation the exact location of all steam and 
water inlets and outlets. When the engines, boilers and auxil- 
iaries are located finally upon the plans, accurate drawings of the 
piping to connect them should be made. The piping should be 
shown in plan and in at least one elevation. The dravrings should 
be to a scale of at least % inch to the foot, and should show the 
location of every fitting and valve in the system. It saves time to 
indicate a valve by drawing correctly the position of its flanges 
and joining them by two crossed lines. W^hen a number of fittings 
are to be placed close together, however, they should be drawn 
accurately and in full, for if this is not done it may happen that 
the piping cannot be put together on account of too much being 
crowded into the space allotted. An accurate drawing would pre- 
vent an error of this kind from occurring. Complete drawings 
result in lower bids, and do away with extras that are usually the 
result of incomplete or inaccurate drawings. 

Principles involved. — The fundamental object to be accom- 
plished in steam piping is, of course, to carry steam without exces- 
sive loss of pressure; and next in importance is the requirement 
of safety, that the condensation loss shall be a minimum and that 
the piping shall not leak. The greatest enemy to safety is the lia- 
bility of water entering the system, or collecting in it, due to con- 
densation ; and it is, therefore, of particular importance that pip- 
ing should be so constructed that it does not contain pockets in 
which water can collect. Pipes are usually proportioned so that 
steam travels at the rate of about one mile a minute, hence if a 
"slug" of water, as a body of water is sometimes called, is picked 
up by the steam and carried along with it an accident is very apt 
to occur, either by the rupture of an elbow, at a change in direc- 
tion of the pipe, or by the water entering the engine cylinder and 



STEAM POWER PLANTS. 71 

wrecking it. In some instances pockets cannot be entirely done 
away with, but where they do occur they should be properly 
drained. Straightway globe valves should not be used in a steam 
pipe, as the valve seat acts like a dam in forming a water pocket. 
Valves of any kind should never be placed so as to form a water 
pocket whether they are closed or open, if it is possible to locate 
them any other way. For instance, one frequently sees the stop 
valve on a boiler placed immediately above the boiler nozzle and a 
vertical section of pipe above the valve leading to an elbow from 
which a horizontal pipe leads to a steam main. When a boiler so 
connected is out of service, water due to condensation accumulates 
in the vertical pipe over the stop valve, and although the pipe 
may be provided with a small drain pipe and valve, experience 
has shown that the latter are not always made use of to draw off 
the water, so that an accident may occur. It is just as effective 
to use an angle stop-valve at the top of the vertical pipe mentioned 
and to pitch the horizontal pipe that leads from it to the main so 
that condensation will flow toward the latter. With such an ar- 
rangement water cannot collect, and hence an opportunity for an 
accident does not exist. 

Steam pipes should always be pitched so that the condensation 
that occurs in them will tend to flow in the direction in which the 
steam is moving, the reason for this being that if it is attempted 
to run condensation against the current of steam, water hammer 
is quite likely to occur, as the water accumulates into a slug, which 
is finally picked up by the steam and carried along until projected 
against a fitting. If one wants to carry steam a long distance, 
from one point to another at a higher level, the pipe should be laid 
at the proper inclination and at frequent intervals, say every loo 
or 150 feet, the line should drop a few feet into a pocket that can 
be drained through a steam trap into a small return pipe running 
back to the boilers. A horizontal pipe should be inclined so that 
the condensation will tend to flow against the current of steam 
only when the pipe is excessively large, so that the velocity of 
steam flow will be much below the usual practice. 

In systems of steam piping connecting several engines and the 
boilers supplying them it is usually the custom to connect each 
boiler with a steam main from which pipes lead to the engines. 
It is well to have this main of quite large size, so that the velocity 
of steam passing through it will be slow enough to allow any 



72 STEAM POWER PLANTS. 

water that might be carried over from the boilers to accumulate 
in the main. The main, of course, should be drained by a pipe or 
pipes leading to a trap. If the main is divided into sections by 
valves, provision should be made for draining each section, for 
the reason that some parts may be shut off at times. Any branch 
to an engine should be connected to the top of the main to prevent, 
as far as possible, water from entering the branch. 

It is impossible to give definite information as to the design of 
piping for all steam plants, for the conditions met with vary so 
much. With electric power-house work, however, this is not the 
case, for the reason that the construction of these plants, unless 
they be very large ones, almost invariably follow one of two types 
that are standard as far as the relative location of engines and 
boilers are concerned. These types are as follows : that in which 
the boilers and engines are placed back to back with a dividing 
wall between, and that with the boiler and engine rooms end to 
end, with the engines and boilers lying in the same direction. As 
far as the piping is concerned, the back to back type is the one 
most to be preferred, on account of the short and direct connec- 
tion between the engines and boilers and the ease with which it 
can be enlarged. With the engine and boiler rooms placed end to 
end the condensation losses in the steam piping are greater, and 
this type of station, ^s far as the piping is concerned, is not easily 
enlarged. 

The steam piping for that type of station in which the engines 
and boilers are placed back to back and separated by a v/all 
usually consists of a feeder from each boiler, connected with a 
main which is supported by the boiler room wall or suspended 
from the roof trusses and also connected to each engine. 

The engine-room floor is usually a little higher than that of the 
boiler room. The main and as much of the piping as possible 
should be located in the boiler room, for the reason that if an ex- 
plosion occurred in some section of the pipe in the boiler room, it 
would be possible after the steam-pressure fell to cut out the dam- 
aged section and operate the rest of the plant. If the engine 
room, on the other hand, was the scene of the explosion and be- 
came filled with steam, the electrical apparatus would, in all prob- 
ability, not be fit for service without considerable overhauling. 

Two valves in a pipe leading from a boiler to a main are much 
more to be preferred than one and are usually provided in large 



STEAM POWER PLANTS. 



73 




Ths ENQiNtCRiNO RrCOR 



SECTION STEAM MAIN. 



ANCHOR FOR STEAM MAIN. 

Figure 22. — Details of Steam Piping, Anderson Station (See Plate G). 

SARGEANT & LUNDY, ENGINEERS. 



74 STEAM POWER PLANTS. 

work. One should be close to the boiler, the other at the mam. 
If there is only one, however, and the steam main is sup- 
ported on a bracket on the boiler room wall, it is a good 
arrangement to carry a pipe with a bend of long radius 
from the nozzle of each boiler to an angle stop valve bolted 
to a nozzle on the top of the main, as shown in Figure 23, 
and to run a connection to each engine from a stop valve similarly 
located. Instead of the angle valve shown in the figure, an elbow 
with a gate valve adjacent to it, with the axis of the valve in a 
horizontal position could be used. The valve in the pipe leading 
from the boiler to the main should not be placed over the boiler 
nozzle and thus form a pocket, for reasons previously explained. 
With both valves close to the main they are easily reached from 
a light walk, suspended from the roof trusses. Another advan- 
tage of placing the valve close to the main is that the condensation 
is less when the valve is closed. Some engineers prefer to place 
the angle stop valve immediately over the boiler nozzle and run 
a horizontal pipe from it to an elbow turning downward to a 
nozzle on the top of the main. The stop valve can then be reached 
by a person standing on top of the boiler setting. The engine 
connection should also be a bend of long radius. These connect- 
ing pipes will then have sufficient elasticity to permit expansion 
and contraction to occur without injury to the pipe. With the 
arrangement suggested there is no chance of water collecting in 
any part of the system, save in the main, and this should be large 
enough so that the water can settle there and pass out by the drain 
pipes. Frequently the pipe leading to each engine is provided 
with a separator close to the throttle valve. Besides intercepting 
moisture in the steam the separator performs another function 
of great value, in that it provides a reservoir of steam close to 
the cylinder, which insures a higher and more uniform pressure 
in the cylinder up to the point of cut-ofif than there would be if it 
were omitted ; and it also reduces the vibrations in the steam pip- 
ing due to the intermittent flow of steam as the valves of the en- 
gine open and close. For these reasons a separator, particularly 
if of large volume, is of much value. 

When the steam piping in the engine room is run in the base- 
ment, the arrangement shown in Figure 24 can be resorted to. 
There the main is close to the floor of the boiler room. It can be 
supported on piers or wall brackets. The stop valve on the boil- 



STEAM POWER PLANTS. 



75 



ers is placed on the nozzle and a pipe with a long' bend drops into 
the top of the main. The branch to each engine is run from an 
angle stop valve on the top of the main to a separator near each 
engine cylinder. This system is as unlikely to have accidents oc- 




P I an 



Figure 24. 



Figure 25. 



cur to it as is the arrangement shown in Figure 23. An excellent 
example of this kind is shown in Plate 7. 

Sometimes the steam piping is put in in duplicate, the two sys- 



re STEAM POWER PLANTS. 

terns dividing at a double nozzle or Y on the boilers, and converg- 
ing at a similar Y close to and connecting with the throttle valve 
of the engine. Duplicate systems were used much more frequently 
in the early days of electric power-house construction than they 
are at the present time. In fact, the opinion is fast becoming uni- 
versal that a duplicate system is an expense that is unnecessary 
with the arrangement of boilers and engines and piping shown in 
Figures 2^ or 24. 

It is the custom in the latest work to subdivide the power 
house into complete and independent units. The plans of the 
Lincoln wharf power house of the Boston Elevated Railway in 
Plate I and Figure 3 shows how the piping is subdivided. By 
closing valves in the main each unit is entirely independent. 

If the power station has the engine and boiler rooms placed end 
to end, as in Figure 25, the arrangement of piping shown there 
is probably the safest. It is arranged on the ring or loop system, 
and valves are so placed that if an accident occurs, the damaged 
section may be cut out and the steam carried around through the 
system in the opposite direction. In the station shown an expan- 
sion joint is placed in the cross connection. The cross-over pipe 
might, perhaps, be omitted. In a station of any size the expan- 
sion in the mains running lengthwise of the engine and boiler 
rooms could be taken care of by anchoring the mains at their* 
middle points, so that the expansion would be divided equally be- 
tween the two ends of the mains. 

Exhaust piping for condensing plants. — A frequent method of 
running exhaust pipes in condensing plants is shown in Figure 
26. Each engine is supposed to be provided with an independent 
condenser and air pump. Two exhaust pipe branches are shown, 
one branch dropping into the condenser and the other branch, 
which contains a reHef valve, leading to the atmosphere. If ad- 
vantageous to do so, the free exhaust pipes can be connected to a 
single pipe leading to the atmosphere. The purpose of the at- 
mospheric connection is to provide means for allowing the steam 
to escape in case something happens to the condenser to prevent it 
from working. The relief valve is nothing more than a large 
check valve that is closed by the pressure of the atmosphere on 
one side, when a partial vacuum exists upon the other. Some- 
times several engines exhaust into one condenser. The general 
arrangement can be the same. Exhaust piping for condensing 



STEAM POWER PLANTS. 



11 



plants should have flanged fittings most carefully put together, 
A leak through a very small hole will greatly affect the vacuum 
and the efficiency of the engine. The principal point to be looked 
after is to have the alignment of the pipe such that there is abso- 
lutely no chance for water to lodge in the piping system, for the 
reason that the water might be sucked back in the engine cylinder 
and destroy it as has frequently occurred. It is practically im- 
possible to drain the exhaust pipe of a condensing engine, except 
toward the condenser, as the system is under a partial vacuum. 
One of the most important points is to have very generously pro- 
portioned exhaust pipes with as direct a run to the condenser and 
as few bends in the pipe as possible. 



£«5/ 



Cylinder. 



r 



Si=t 



Primary 
}jeafer. 




THE Engineer(no record. 



Figure 26. 



Piping Between Cylindeis of Compound Engines. — It is usually 
the custom in installing a cross-compound engine to arrange the 
piping between the cylinders so that high pressure steam may be 
admitted to the low pressure cylinder as well as the high pressure 
and to provide the necessary exhaust pipes so that both cylinders 
may be used at the same time as simple engines. If the engine 
is to be run condensing, it is sometimes so piped that the high 
pressure cylinder may run as a simple non-condensing engine 
while the low pressure cylinder may run as a simple condensing 
or non-condensing engine as may be desired. Designers have 
gone so far as to provide for running high pressure cylinders as a 
simple condensing engine and the low pressure cylinder a simple 



78 



STEAM POWER PLANTS. 



non-condensing engine although ordinarily intended to operate as 
an engine of the cross-compound condensing type. Various ar- 
rangements for accomplishing the purpose mentioned are shown 
in Plate 3 and in Figure 18. 

Exhaust piping for non-condensing plants. — In non-condens- 
ing plants the exhaust steam can be carried long distances for 
heating or for manufacturing purposes, provided the pipes carry- 
ing it are large enough. When exhaust steam is thus utilized, 
the pipe carrying the exhaust steam from the engines to the outer 
air, which is known as the atmospheric exhaust, or the free-ex- 
haust pipe, is provided with a back-pressure valve, the function 
of which is to preserve a sufficient pressure in the exhaust piping 
to cause the exhaust steam to flow through a system of pipes, 
also connected with this free-exhaust pipe, to the places where it 






ToHeatinq 
Systr-^ 



Boilers. 



q:^ 



QlJ^ 



f^^ 



Watir Hcafa- Feed Wafer lilain.^ Inficf^ i^^ 

rQH Separator ^^ Exhaust Pi pes. 




Figure 27. — Exhaust and Feed Piping for Non-Condensing Plant. 



is to be used. These back-pressure valves are designed so as to 
open when the pressure in the exhaust system exceeds a certain 
amount, and thus allow^ sufficient steam to escape to reduce the 
pressure to that desired. It sometimes happens when exhausi 
steam is used for heating or for manufacturing purposes, that 
the supply is not sufficient to meet the demand, and if this is 
likely to occur, it is the custom to run a live-steam pipe from the 
high-pressure piping to the exhaust piping, and to place in this 
connecting pipe a reducing valve which automatically opens and 
allows live steam to enter the exhaust system when the pressure 
in the latter falls below that which it is desired to maintain. 

When a system for utilizing exhaust steam is employed, it is 
frequently arranged in the manner shown in diagram by Figure 



STEAM POWER PLANTS. 79 

2y. A grease separator should be provided to remove as much 
oil as possible from the exhaust steam, after which the steam is 
passed through the feed-water heater. The arrangement shown 
is designed for a feed-water heater of the closed type. From the 
heater the pipe branches, one branch supplying steam for heating 
or for a manufacturing purpose — this branch furnished with a 
high-pressure connection run from the boiler and containing a re- 
ducing valve. The other branch leads to the atmosphere, and it 
is provided with the back-pressure valve. The top of the free- 
exhaust pipe should have an exhaust head for intercepting the 
moisture that is blown out of the pipe by the exhaust steam. This 
head should have a drain pipe to a sewer or to waste. 




Figure 28. 



Most power plants have a basement under the floor of the en- 
gine room, and in steam plants for buildings the exhaust piping 
is frequently run in covered trenches. When the exhaust piping 
is below the floor, a satisfactory method of connecting the feed- 
water heater is shown in Figure 28. The steam may pass 
through the heater or around it through the by-pass by properly 
adjusting the valves. 

Care of drips. — The drainage from any part of the piping 
system is valuable on account of the value of the water, and the 
heat in the water that would be lost if the condensation was al- 



^0 STEAM POWER PLANTS. 

lowed to go to waste. By condensation is meant water due to 
condensation in the pipes. Sometimes the saving that is due to 
returning high-pressure condensation to the boilers is not suffi- 
cient to warrant the expenditure for the apparatus necessary to 
do this, but that is a point which must be determined for each 
case. Condensation from exhaust-steam pipes can sometimes 
well be allowed to go to waste, for the reason that it generally 
contains more or less oil; and the chance of this doing injury to 
the boilers is apt to be too great for the saving that would follow 
its utilization. If it is used, the water should be filtered. 

There are various methods of returning high-pressure conden- 
sation to the boilers, and the most common are the Holly system 
and the ''steam loop," both patented systems controlled by West- 
inghouse, Church, Kerr & Company, by means of the automati- 
cally-governed steam pump and receiver and by means of a re- 
turn trap. With the pump and receiver all high-pressure drip 
pipes, from separators, steam jackets on the cylinders, from re- 
heating receivers placed between the cylinders of compound and 
triple-expansion engines, and all other points from which water 
is drained can be connected to a main leading to an automatic 
pump and receiver. Each drain pipe should have a steam trap, 
if there is any chance of their being under different pressures. 
The automatically-governed pump can discharge the water into 
the boiler feed-pipe between the boiler feed-pump and the boilers. 
With very long steam pipes which have to be drained at several 
points, the drainage can be draw^n off by a steam trap discharg- 
ing into a return pipe leading to an automatic pump and receiver 
at the boiler-house. If the inclination of the steam pipe is such 
Ihat the water will not run back by gravity in the return pipe to 
the boiler house, the drip can be carried to the lowest point in the 
system and an automatic pump and receiver, operated by steam 
from the main pipe, can be located there and used to pump the 
water up hill and back to the boiler house ; that is, of course, pro- 
vided the saving will warrant this arrangement. All high-pres- 
sure drip lines should be thoroughly covered with a non-con- 
ducting covering. 

Low-pressure drips contain the condensation drawn from pipes 
■carrying exhaust steam, steam condensed in feed-water heaters 
•of the closed type, the drip from engine and pump cylinders and 
the drip from grease separators. All of this condensation should 



STEAM, POWER PLANTS. 



81 



be thrown away on account of the grease that it contains, unless 
some form of oil filter is used. All low-pressure drips should 
be trapped independently into a drip main which can be led to 
any convenient place, such as the sewer, the pipe carrying off the 
discharge from the condenser, etc. 

Feed-water piping. — Feed-water piping is sometimes put to- 
gether with screwed and sometimes with flanged fittings, and these 
are either of brass or cast iron. The pipe is of brass or extra 
heavy wrought iron. The screwed fittings are said to be capable 

Boifers.. 



QUD 



(Check Valvz. 



SI^ 



■Injector. 



Auxiliary Heater - 
B/'Pass.- 



^ 



(^rimc^) Heaf<Q 







Air Pump 

Th( ENOiNEERINa RECORD. 

Figure 29. — Feed Piping for Condensing Plant. 



of Standing a pressure of 150 pounds, but for pressure over 125 
pounds flanged fittings are frequently used. It is better to use 
elbows with a long radius to reduce friction. Gate valves should 
be used instead of globe valves, for the same reason. 

An arrangement for feed-water piping for a typical plant 
equipped with surface condensers is shown in diagram by Figure 
29. The plant is supposed to contain three engines, each with an 
independent air pump and surface condenser, two boiler feed- 
pumps, a primary heater in the exhaust pipe of each engine, be- 
tween the engine and surface condenser, and a single auxiliary 
heater of the closed type receiving the exhaust steam of the air 
pumps and the boiler-feed pumps. The steam condensed in each 
condenser is drawn therefrom by the air pumps and forced into 
a hot well, from which the boiler-feed pumps draw their supply. 



82 



STEAM POWER PLANTS. 



For occasionally replenishing the water from the condensers and 
supplying fresh water when needed, a fresh-water pipe is led to 
the hot well, and its supply can be controlled by a float valve or 
ball cock, so that fresh water will flow in the hot well in case the 
boiler-feed pumps draw water faster than it is discharged from 
the air pumps an occurrence that is unlikely to happen. The 
boiler-feed pumps are in duplicate. It is a good investment to 
put a water meter in the feed line, and one capable of measuring 
hot water should be used. The meter should have a by-pass and 




CityMah^^^ 



Efevation 

Figure 30.^ — Feed Piping Boston Electric Light Company's Station. 



be located at the pressure side of the pump, as shown. From the 
feed pumps the water is forced through the primary heaters and 
then through the auxiliary heater to the boilers. If the hot well 
is not provided with sponges or some material arranged to filter 
the oil from the air pump discharge, a cloth filter should be placed 
between the feed pumps and the boilers. Each heater should 
have a by-pass, and in the pipe leading to each heater two valves 
should be placed, one used as a stop valve and the other as a regu- 
lating valve, which should be adjusted when the plant is started, 



STEAM POWER PLANTS. 



83 



SO that approximately equal amounts of water will pass through 
the heaters. It involves a little more complication to do this, but 
it insures each heater doing its full work. 

The arrangement shown in Figure 29 provides for the use of a 
heater of the closed type between the engine and condenser for 
of course an open heater could not be used in such a situation. 
It is not often the custom to place a heater between the engine 
and condenser and where that is not done an open heater might 
be used to receive the exhaust steam of the auxiliaries, and if so, 




Figure 31. — Arrangement Auxiliaries Boston Electric Light 
Company's Station. 



the arrangement of the feed-water piping would have to be dif- 
ferent from that shown. If the plant shown diagrammatically in 
Figure 29 was provided with jet condensers the boiler feed pumps 
might be arranged to draw their supply from the air pump dis- 
charge, as well as from the source of the fresh water supply and 
pump it through the heaters to the boilers. If ample feed water at 
low cost was available the air pump discharge would probably be 
allowed to go to waste because of the grease in it and the pumps 



84 



STEAM POWER PLANTS. 



connected to draw fresh water. If the latter was under pressure 
the water could be passed to an open heater first and the pump 
arranged to draw the water from it. This arrangement combined 
with an economizer is shown diagrammatically in Figure 32. If 
a surface condenser was used the air pump discharge might be 
led to an open hot well, arranged to filter the water by means of 
sponges or excelsior, etc., located at a higher elevation than the 
heater so the water would flow to the heater by gravity and from 
the heater to the feed pumps at a lower elevation than the heater 
so that the pump suction would be under pressure. If the filter 
was of the closed type containing cloth or similar material it 
would have- to be placed between the pumps and the boilers. 
High pressure drips could be trapped into the heater, returns from 
the heating system could be connected, with it and fresh cold 
water could be added to the heater bv a float valve when the de- 



Boilzrs. 



O-O 



CXS) 



&X) 



fCheck Valvz. 



.j~W '. Injzcfor Mam. * I " 



Injechr. 

i- 



I -^ I feed] \fi/mps\ L 

-MSEIIJ-^ fly 



Open Hzahiy By-Pass.' 



— , S—AIIHiq 



(ColdW ahrSuppJy. 



-„ ... High Pressure Drips, 

^Pass. Returns from HeahngSysfem Efc. 
entzf Heaiac. 



?f Pass. 



Figure 32. — Feed Piping With Open Heater. 



mand of the pumps was in excess of the water entering the 
heater from the condensers, heating system, drips, etc. The 
boiler feed pumps would have to pump hot water with this ar- 
rangement, hence they should be constructed to do this. The 
pumps could deliver w^ater to the boilers direct or first through 
an economizer where the water would be heated further by the 
waste gases from the boiler. An economizer is placed between 
the pumps and the boilers. Arrangements should be made to by- 
pass all heaters, economizers, meters, etc. 

If a live steam purifier is used, which is a heater in which the 
feed water is exposed to the action of steam at full boiler press- 
ure to precipitate scale forming salts in the purifier instead of hav- 
ing them precipitated in the boiler. The purifier is elevated 



STEAM POWER PLANTS. 



85 



above the boilers and receives the feed water after it has passed 
through all other heaters; and it is connected so that water will 
flow from it to the boilers by gravity. 

In Figure 29 one end of the feed-water main in the boiler room 
is provided with an injector connected to the fresh-water supply. 
It would be a better arrangement, perhaps, to have an indepen- 
dent main from the injector, the main connecting with the feed 
pipe to each boiler through stop valves so that water f^om the in- 







Figure 33. — Pipe Bracket Designed by Sheaff & Jaasted. 



jector or the feed pump could be supplied to any boiler indepen- 
dent of the others as shown in Figure 32. 

The method of running feed mains in a boiler room varies. 
Horizontal tubular boilers are frequently set with a number of 
boilers in one battery. Sometimes therefore, the feed main is 
run along the fronts of the boilers just above the fire doors. 
Water-tube boilers are generally set two in a battery, so that if 
a pipe extends across the front it blocks the passageway between 
the batteries. W'ith this type of boiler the feed main is sometimes 



STEAM POWER PLANTS. 



run In a covered trench in the floor along the fronts of the boilers.' 
Again, the mains are run on top of the setting. In the latter 
event a branch from the main should extend to the boiler front, 
at an elevation low enough so that the regulating valve, which 
should be of the globe type, may easily be reached by the boiler 
attendant. A check valve should be placed in the pipe, as shown. 

Feed-water piping for non-condensing plants with the closed 
type of feed water heater is shown in diagram in Figure 27. It 
is supposed that exhaust steam is used for heating and that the 
condensation is returned to the boilers. This may be brought 
back to one of the boiler-feed pumps, which can be connected 
to a return tank receiving the condensation in the heating sys- 
tem. The pump draws water from the tank and forces it through 
the feed-water heater to the boiler. A fresh-water pipe is led to 
the return tank and the supply is controlled by a float valve. If 
a feed-water heater of the open type is used, the condensation 
from a heating system is carried back to the heater, and usually 
enters it at the side or bottom and thus does away with the auto- 
matic pump and receiver. The boiler-feed pump draws its sup- 
ply from the heater and forces the water to the boilers. Fresh 
water under pressure, controlled by a float valve or ball cock in 
the heater, is supplied to the heater at the top, and it falls to the 
bottom in direct contact with the exhaust steam and is thus 
heated. Cold water is only supplied when the boiler-feed pump 
draws the water from the heater so fast that the water surface 
falls below a certain level. 

In electric stations it is frequently the practice, for safety^s 
sake, to use a duplicate feed main from the pump to the boilers. 
With such an arrangement it is possible to test a boiler or group 
of boilers. If the steam piping is arranged so that one or more 
boilers can supply any one engine independently of the others, 
the duplicate boiler-feed main is of considerable value, for with 
such a duplicate system the steam used by an engine can be 
measured at any time and the condition of the engine determined. 
Boiler feed pumps should always be in duplicate. 

Kind of pipe. — ''Standard" sizes of steel pipe are used for steam 
piping. Table I. contains the various dimensions of pipe, those 
up to and including lo-inch pipe being the Briggs standard. The 
other sizes are in common use. As ordinary merchant pipe may 
vary in thickness from the standard, ''full weight" pipe should be 



STEAM POWER PLANTS. 87 

asked for. Full weight pipe may vary 5 per cent, from the stand- 
ard thickness. In the connection between a boiler and a steam 
main, or the main and the engines, long bends made of pipe are 
an advantage, for several reasons. First, they reduce the fric- 
tion very much; second, their use reduces the number of joints 
likely to leak; third, such a connection is very much more flex- 
ible than one composed of two straight pieces of pipe connected 
by an elbow. Their greater flexibility is of great advantage in 
taking care of expansion after the piping is in place, and further- 
more, they are much easier to connect when erecting the piping. 



TABLE I.— DIMENSIONS OP STANDARD WEIGHT PIPE. 

a 



a t %i Ss diio?idi:S 



-o 



'B I =^§« c^ ^§ ■ ^ ^^-S^^^-^ 

o w c c<2t; s c cu ^ ■'^^ -^ 

'^ pj^ o p.- bD^^ 'o tifl^ bfi -go .-go . 

a 3^1) r: J:+- '^'^Mw !3 a; -3.2 f> •- 1> cS -r > ji.S 

Ins. Ins. Ins. Ins. Feet. Ins. Feet. Lbs. Lbs. Lbs. 

1 1.315 0.134 1.048 2.903 0.8627 166.9 1.670 

IVi 1.66 0.140 1.380 2.301 1.496 96.25 2.258 

11/2 1.90 0.145 1.611 2.01 2.038 70.65 2.694 

2 2.375 0.154 2.067 1.611 3.355 42.36 3.600 

21/2 2.875 0.204 2.468 1.328 4.783 30.11 5.773 

3 3.50 0.217 3.067 1.091 7.388 19.49 7.547 80 113 
31/2 4.00 0.226 3.548 0.955 9.887 14.56 9.055 107 151 

4 4.50 0.237 4.026 0.849 12.730 11.31 10.66 138 104 
41/a 5.00 0.247 4.508 0.765 15.939 9.03 12.34 173 243 

5 5.563 0.259 5.045 0.629 19 990 7.20 14.: 218 305 

6 6.625 0.280 6.065 0.577 28.889 4.98 18.'^67 315 442 

7 7.625 0.301 7.023 0.595 38.737 3.72 23.27 422 592 

8 8.625 0.322 7.982 0.444 50.039 2.88 28.177 545 764 

9 9.625 0.344 9.001 0.394 63.633 2.26 33.70 694 974 

10 10.75 0.366 10.019 0.355 78.838 1.80 40.06 872 1.223 

11 12.00 0.375 11.25 0.318 98.942 1.455 45.95 1,079 1.514 

12 12.75 0.375 12.000 0.293 116.535 1.235 48.98 1,275 1,78S 

13 14.00 0.375 13.25 0.273 134.582 1.069 53.92 1,468 2.060 

14 15.00 0.375 14.25 0.254 155.968 .923 57.89 1,702 2,385 
16.00 0.375 15.25 0.238 177.867 .809 61.77 1,940 2.722 
18.00 0.375 17.25 0.212 225.907 .638 69.66 2.462 3.452 
20.00 0.375 19.25 0.191 279.720 .515 77.57 3,050 4,275 
22.00 0.375 21.25 0.174 354.66 .406 85.47 3,870 5.425 



No matter how much care is taken in facing the flanges oft* 
square, it almost always happens that the flanges of the boiler 
nozzles are not in perfect alignment, or exactly horizontal, so that 
a considerable strain is introduced in the piping in forcing the 
abutting flanges to a seat. It is much better to make the bends 
in the piping of steel than copper, although the latter has been 
used to some extent. At the temperature the copper is subjected 
to in brazing the joint, the fibrous nature that copper acquires in 
rolling is destroyed and a serious reduction of its tensile strength 



88 STEAM POWER PLANTS. 

and ductility results. Mr. James B. Berryman of the Crane Com- 
pany states that unless the bends are of very short radius they are 
generally made of standard pipe for pressures of 125 pounds or 
less, full weight pipe up to 175 pounds, and extra heavy pipe for 
higher pressures! 

Ske of steam pipes, — It has been the custom to so proportion 
steam pipes for engines that the maximum velocity of steam flow- 
ing through them will be about 6,000 feet per minute. The pipe 
size can be obtained by assuming that the area of the steam pipe in 
square inches multiplied into the maximum velocity of steam in feet 
per minute is equal to the piston area in square inches multiplied in- 
to the piston speed in feet per minute. If the cut oil is at one-third 




Th£ Encineeiuno RECOWa 

Figure 34. — Pipe Bracket. 



stroke the average velocity of steam would then be about 2,000 
feet per minute. Friction w^ould cause a considerable drop in 
pressure, with small sizes of pipe, when proportioned by this 
rule. Some experiments upon the flow of steam in pipes 
in a paper in volume XX. Transactions of The American 
Society of Mechanical Engineers,' by Professor R. C. Car- 
penter, give some data that is of value. The tests were made 
upon I, i>^, 2 and 3-inch pipes with lengths varying from 90 to 
250 feet. The formula derived from the experiments checks very 
closely with the results obtained by M. Ledoux, who experi- 



STEAM POWER PLANTS. 89 

merited with pipes varying from 1.85 inches to 3.94 inches in 
diameter and with lengths varying from 328 feet to 1,082 feet. 
Professor Carpenter uses the formula 

P= ^i'{ ^+ ) ,, ,5 

20.663 \ d / ^^ 

in which P equals the loss of pressure in pounds per square inch, 
d the diameter of the pipe in inches, W the flow of steam in pounds 
per minute, w the flow in pounds per second, D the density or 
weight per cubic foot, L the length of pipe in feet and K a constant 
taken, as a result of the experiment, at .0027. Table 11. , which 
was calculated by Mr. E. C. Sickles, is based upon the formula 
and was deduced by making every factor constant except the 
diameter, length of pipe, and discharge. The left-hand vertical 
column of the table contains the diameters {d) of the pipes, and 
the top horizontal column the length (L) in feet, while the body 




Figure 35. — Pipe Support Designed by Dean & Main. 



of the table gives values of {W) the pounds discharged per 
minute. Prof. Carpenter explains the table as follows: 

"Thus, for instance, a lo-inch pipe 250 feet long will deliver 
712 pounds of steam per minute with a drop of one pound in 
pressure, if there exists an average absolute pressure of 100 
pounds ; or, if all other conditions hold except the length of 
pipe, which varies, it may be seen that for 100 feet the discharge 
is 1,126 pounds, for 400 feet 563 pounds, and so for any num- 
ber of feet given in the table. 

"If any intermediate length of pipe is used other than those 
given in the tables, the discharges given by the tables may be 
corrected bv consideration of the fact that the wcii^ht of dis- 



90 STEAM POWER PLANTS, 

charge is inversely proportional to the square root of the length 
of the pipe. 

*'To meet the conditions where other average absolute pressures 
than 100 pounds exist, and higher drops than one pound are as- 
sumed, it is only necessary to use suitable factors which are 
calculated by means of the fundamental formula, and graphically 
represented by Curves i and 2, Figure 36. 



1.540 
1.500 
1.460 
1.420 
1.880 
1.340 
1.300 
1.260 
1.220 
1.180 
1.140 
1.100 
1.060 
1.020 
0.980 
0.940 
0.900 
0.860 























2NJ 






























































\, 






























































< 




























































N 


^, 




























































\ 






























/ 
































\ 
























/ 


k 


































^ 


V 




















k 








































N 


















y 












































\ 












t" 


^ 














































\ 


























































\ 






/ 


< 






















































\r 


y 


























































A 






















































f 


/ 




\ 






















































/ 






^ 


\ 
















































( 


/ 










\ 
















































/ 














K 












































^' 
















\ 








































/ 


^' 




















\ 






































^ 






















\ 


































/ 


/ 
























• c 


\ 








. 






















/ 


[5^ 




























\ 




























f 


/ 






























) 


\ 


























^ 
































-; 


\ 






















1 


/' 




































\ 






















/I 
























































/ 


























































/ 














































5 












/ 
















































\ 










/ 


















































\ 








J 


k 


















































^ 

( 








/ 






















































\ 




/ 












^ 


LV€ 


ra 


?e 


Ste 


an 


Ip 


res 


su 


re 


in 


Po 


pn 


Is 


Ab 


sol 


Ut( 


5. 










\ 




80 


S 





100 


L 





120 


130 


140 


h 





160 


1 


~0 


180 


V 





200 


2 


220\230 






- 


1 




_ 


1 


1 


1 


















r 




lU 



4.40 
4.20 
4.00 



3.60 » 
I 

3.40 2 
at 

3:20! 

a 
00 « 

2 

2.80 O 



2.60 



22 21 20 19 18 37 16 15 14 13 12 11 10 9 8 7 6 5 4 
Pounds— Drop In Pressure 

Figure 36. 



2 1 



2.20 tS 

2.00 

1.80 

1.60 

1.40 

1.20 

1.00 



"As an illustration of the use of the tables and curves, suppose 
it is desired to find what size pipe will be required to deliver 
i,ooo pounds of steam per minute a distance of i,ooo feet, the 
initial pressure of the steam being 157.5 pounds, and the final 
152.5 pounds by gauge. Solution — It will be best to reduce all 



STEAM POWER PLANTS. 91 

conditions to those of the tables and find the discharge, and from 
this the size of the required pipe. Looking at Curve 2, we find 
the factor of discharge for a 5-pound drop is about 2.23 times 
that for a i -pound drop. Therefore, dividing the required dis- 
charge of 1,000 pounds by 2.23, we have about 450 pounds dis- 
charge for a I -pound drop. 

TABLE II.— FLOW OF STEAM IN PIPES. DELIVERY IN POUNDS PER 
MINUTE BY PIPES OF GIVEN DIAMETERS AND LENGTHS. (ABSO- 
LUTE PRESSURE 100 POUNDS— DROP IN PRESSURE ONE POUND.) 











Length in Feet. 












50 


100 


150 


200 


250 


300 


350 


400 


500 


600 


% 


1.55 


; 1.10 


.898 .700 .698 


.633 


.589 


.550 


.491 


.450 


1 


3.10 


1 2.20 


1.79 


1.55 


1.39 


1.26 


1.17 


1.10 


.982 


.900 


IVL 


6.9C 


1 4.88 


3.93 


3.44 


3.08 


2.81 


2.62 


2.44 


2.18 


1.96 


IV2 


9.29 


1 6.52 


5.83 


4.62 


4.14 


3.77 


3.50 


3.26 


2.91 


2.67 


2 


21.6 


15.2 


12.50 


10.8 


9.82 


8.82 


8.37 


7.63 


6.81 


6.23 


21/2 


35.9 


25.4 


20.8 


17.9 


16.2 


14.62 


13.6 


12.7 


11.3 


10.4 


a-g 








Length 


IN Feet 












100 


250 


400 


550 


700 


850 


1,000 


1,300 


1,600 


1,750 


3 


46.0 


29.2 


23.0 


19.6 


17.4 


15.8 


14.5 


12.7 


11.5 


11.0 


3M 


i 69.5 


44.6 


34.7 


29.6 


26.3 


23.8 


22.0 


19.2 


17.4 


16.6 


4 


97.6 


61.8 


48.8 


41.5 


36.7 


33.5 


30.8 


27.1 


24.4 


23.3 


41/2 132.9 


84.1 


66.45 


56.6 


50.1 


45.6 


42.0 


36.75 


33.2 


31.8 


5 


180.7 


114.3 


90.3 


76.9 


68.2 


62.1 


57.1 


50.0 


45.2 


43.2 


6 


296.5 


187.4 


148.2 


125.8 


111.8 


101.8 


93.7 


82.2 


74.1 


71.0 


7 


437 


276 


218 


186 


165 


150 


138 


121 


109 


104 


8 


624 


394 


312 


266 


236 


214 


197 


173 


156 


149 


9 


853 


539 


426 


363 


322 


992 


269 


236 


213 


204 


10 ; 


1,126 


712 


563 


480 


425 


386 


356 


312 


281 


269 


11 : 


1,447 


915 


723 


617 


546 


496 


457 


401 


361 


346 


12 ; 


1,887 


1,192 


943 


803 


714 


648 


598 


523 


472 


451 


13 : 


2,238 


1,415 


1,119 


954 


846 


767 


707 


620 


559 


535 


S 








Length 


IN Feet 










•2s 


100 


200 


300 


500 


800 


1,000 


1,400 


1,800 


2,000 


2,200 


14 


2,714 


1,920 


1,567 


1,213 


959 


858 


725 


639 


606 


578 


15 


3,250 


2,300 


1,873 


1,453 


1.149 


1,028 


868 


766 


726 


693 


16 


4,000 


2,830 


2.315 


1,785 


1.413 


1,268 


1.072 


945 


895 


854 


17 


4.500 


3.210 


2.635 


2.021 


1..591 


1.424 


1.200 


1.061 


1.006 


962 


18 


5,211 


3,685 


3.008 


2,330 


1.843 


1.648 


1.393 


1.228 


1.165 


1.111 


19 


5.992 


4.237 


.3.459 


2.680 


2.119 


1,895 


1.602 


1.412 


1.340 


1.278 


20 


6,839 


4,835 


3.948 


3.059 


2,418 


2.163 


1,828 


1,612 


1.529 


1.458 


22 


8.743 


6.183 


5,048 


3.910 


3.093 


2.765 


2.. 337 


2,061 


1.955 


1.864 


24 ; 


113,08 


7,990 


6,535 


5,065 


3,995 


3,580 


3.023 


2,665 


2,535 


2,415 



"Again, the average pressure is 155 -|- 15, or 170 pounds abso- 
lute, and from Curve I it may be found the factor of discharge is 
1.248 greater than for 100 pounds absolute. Therefore, dividing 
450 pounds by 1.284 we have 350 pounds on the basis of the con- 
ditions given by the tables; and looking under 1,000 feet lengths 
for the discharge nearest to 350 pounds, we find a lo-inch pipe 



92 STEAM POWER PLANTS. 

discharges 356 pounds per minute; therefore, it would be satis- 
factory." 

Size of exhaust pipes. — Exhaust pipes should be proportioned 
for a much lower velocity of steam than high pressure pipes. 
The loss of a pound pressure between the engine and con- 
denser means a very much greater increase in the amount of 
steam required to run the engine than would be occasioned by 
the loss of several pounds in the initial pressure, particularly 
with engines operating with low mean effective pressures. No 
general rule can be given for proportioning exhaust pipes. It is 
best to calculate the velocity that would occur in a pipe of a cer- 
tain size for an assumed loss in pressure by means of formula for 
the flow of steam through pipes. 

Kind of fittings. — There are two kinds of fittings used in 
steam piping, the screwed and the flanged fittings. The former, 
as the name implies, are put together with a screw thread, while 
the flanged fittings are bolted together. Screwed fittings are used 
to some extent in plants where the steam pressure is low, 80 
pounds or under, and sometimes with higher pressures. Their 
use, however, seems to be going out for power plant work. The 
most used type of flange is shown in Figure 37. The pipes are 
screwed into the flanges as shown. On July 18, 1894, committees 
of the American Society of Mechanical Engineers, of the National 
Association of Steam and Hot- Water Fitters, and of manufac- 
turers of fittings, met and adopted a schedule for the dimensions 
of flanges and this schedule is know^n as the A. S. M. E., or the 
"Master Steam Fitters" flange schedule. This schedule is printed 
in Table III. upon another page. Flanges dimensioned in accord- 
ance with this schedule are considered strong enough for a steam 
pressure of 100 pounds. For higher pressures, a schedule shown 
in Table IV. was adopted June 28, 1901, and this is suitable for 
pressures from 125 to 225 pounds per square inch. Flanged fit- 
tings, that is elbows, ties, crosses, etc., are made by a number of 
manufacturers and attention is drawn to the fact that the face to 
face and the face to axis dimensions vary with the different 
makes although the flange dimensions are standard. Specifications 
for flanges should require that the holes be drilled in the flange 
to straddle a vertical plane passing through the axis of the pipe. 
In the best work the pipe and flange are carefully threaded and 
the pipe screwed into the flange until it projects slightly beyond 



STEAM POWER PLANTS. 



93 



its face. The inner circumference of the flange at the face of the 
flange is then struck with a hammer, or peaned, as it is called. 
The pipe and flange are then put into a lathe where both are 
faced off. It is very essential that the pipe and flange be faced 

TABLE III. — SCHEDULE OF STANDARD FLANGES ADOPTED JULY 18, 1894, 
BY A COMMITTEE OF THE MASTER STEAM AND HOT WATER FITTERS' 
ASSOCIATION, AMERICAN SOCIETY OF MECHANICAL ENGINEERS AND' 
VALVE AND FITTING MANUFACTURERS. SUITABLE FOR PRESSURES 
UNDER 100 POUNDS PER SQUARE INCH. 









Size 


Size 












Num- 


of bolts, 


of bolts, 


Flange 




Width 


Size of 


Diameter 


ber 


pressure 


pressure thickness Flange 


of 


flange, pipe 


of bolt 


of 


under 


80 lbs. 


at hub for 


thickness 


flange 


size X diam. 


circle. 


bolts. 


80 lbs. 


and over. 


iron pipe. 


at edge. 


face 


2x6 


4% 


4 


y2x2 


%x2 


1 in. 


% 


2 


2y2X 7 


5y2 


4 


V2 X 214 


% X 21^ 


lys 


"/i« 


2% 


3 X 71/2 
SVaX SVa 


6 


4 


V2 X 21/2 


% X 2y2 


iy4 


% 




7 


4 


Vo X 21/4 


% X 21/2 




"/i« 


21^ 


4x9 


7y2 


4 


% X 2% 


% X 2% 


1% 


"A« 


21/^ 


4y2x 9% 


7% 


8 


%x3 


%x3 


1% 


"/i« 


2% 


5 xlO 


81/2 


8 


%x3 


3/4x3 


1% 


'V,p. 


2y2 


6 xll 


9y2 


8 


%x3 


%x3 


1% 


1 


21/2 


7 X 12% 


10% 


8 


% X 31/4 


% X 31/4 


1% 


lVn« 


2% 


8 X ISVa 


11% 


8 


% X 3% 


%x3y2 


1% 


lys 


2% 


9 xl5 


131/4 


12 




% X 31/3 


1% 


lys 


3 


10 xl6 


14% 


12 


% X 3% 


Ys X 3% 


2 


1V,„ 


3 


12 xin 


17 


12 


% X 3% 


Ys X 3% 


2 


ly* 


3y2 


14 x21 


18% 


12 


% X 41/4 


1 X414 


2 


1% 


31/2 


15 X 22 V4 


20 


16 


%x4i4 


1 X414 


2 


1% 


3% 


16 X 231/2 


211/4 


16 


% X 41/4 


1 X 41/4 


2y4 


1V,« 




18 X 25 


22% 


16 


1 x4% 


lys X 4.% 




1 "An 


34 


20 X 271/2 


25 


20 


1 x5 


lysxs 


— 


3% 



TABLE IV.— SCHEDULE OF STANDARD FLANGES FOR EXTRA HEAVY 
STEEL PIPE, FITTINGS AND VALVES ADOPTED JUNE 28, 1901, BY 
VALVE AND FITTING MANUFACTURERS. SUITABLE FOR PRESSURE 
FROM 125 TO 250 POUNDS PER SQUARE INCH. 



Size 


Diameter 


Thickness 


Diameter of 




Diameter of 


of pipe. 


of flange, 


of flange, 


bolt circle. 


Number of 


bolts, 


inches. 


inches. 


inches. 


inches. 


bolts. 


inches. 


2 


61/2 


Vs 


5 


4 


% 


21/2 


71/2 




5% 


4 


% 


3 


sy* 


IVs 


6% 


8 


% 


3y2 


9 


lVl6 


7^4 


8 


% 


4 


10 


iy4 


7% 


8 


% 


4ya 


loya 


1V16 


81/2 


8 


% 


5 


11 


i|. 


914 


8 


Q^ 


6 


i2y2 


10% 


12 


% 


7 


14 




iiys 


12 


% 


8 


15 


1% 


13 


12 


iZ 


9 


16 


1% 


14 


12 


% 


10 


17ya 


1% 


l?l 


16 


T ^ 


12 


20 


2 


16 


%• 


14 


221/2 


2y8 


20 


20 


%■ 


15 


23y2 


2Vi6 


21 


20 


1 


16 


25 


214 


22y2 


20 


1 


18 


27 


2% 


241/2 


24 


1 


20 


291/2 


2y2 


26% 

28% 


24 


i3i 


22 


311/2 




28 


1^ 


24 


34 


2% 


311/t 


28 


1% 



off in the lathe in order that the face of the flange will be perpen- 
dicular to the axis of the pipe. Pipe over i8 inches in size can- 
not be threaded so the flanges are riveted on pipes over that size, 
or else shrunk on. In the latter case an accuratelv bored flanere 



94 



STEAM POWER PLANTS. 



is heated and forced on the end of the pipe. Sometimes rivets are 
used with smaller pipe than i8 inches but more often with larger 
sizes. Cast-iron flanges riveted to the pipe are apt to leak as it is 
very difficult to make a joint that will stay tight. 

The difficulty with the flange shown in Figure 37 is the ten- 
dency to leak through the thread. This can be overcome by good 
workmanship, and some manufacturers have devoted a great deal 




t 



Figure 41. 



The Engineering RECOR D. 

Figure 42. 



of attention to making flanges of this type for high steam pres- 
sures. This type of flange is frequently put together with a cop- 
per gasket, either in the form of a flat or a corrugated ring. 
There are various patented packings that have also given excel- 
lent satisfaction. In the flange shown by Figure 38, which has 



STEAM POWER PLANTS. 95 

been used with a good deal of success, there is a circular tongue 
and groove, as shown, the groove containing a ring of copper as 
a gasket. One objection to this flange is that in places where 
the piping is concentrated and the connections short, it is difficult 
to spring the flanges apart a sufficient amount to take out a sec- 
tion of pipe for repairs. 

The objection to any screwed flange is the tendency, unless the 
workmanship be of the best, for steam to leak through the joint 
between the flange and the pipe. A method of overcoming this 
leakage is shown in Figure 39. The sketch from which the cut 
was made was furnished by Mr. George L Rockwood, Mem. Am. 
Soc. M. E., w^ho designed the flange. The pipe is a steel boiler 
flue, and the flange is slipped over it, and the end of the pipe 
heated and flanged, as shown. The faces of the flange are cut 
away so as to caulk the joint. The "Walmanco" joint, made by 
the Walworth Manufacturing Company, has a recess in the flange 
in which the pipe is expanded as shown in Figure 40. This joint 
has been used successfully to a considerable extent. 

Cast iron pipe with flanges cast on the ends as shown in Figure 
41 have been used by some engineers but the material is so 
treacherous in nature that its use is to be deprecated except for 
feed mains where the water is bad. 

Wrought pipe with forged wrought flanges welded on the end 
of the pipe, shown in Figure 42, introduced within the last two 
or three years, seems destined to be used considerably in the 
future. The process of manufacture has been developed by the 
National Tube Company, which stated that in making the pipe 
a forged flange is bored out and forced on to the end of the pipe. 
It is then heated in a furnace and welded by means of a hammer. 
The flange is then faced and the bolt holes bored out. The pip- 
ing is usually put together with a corrugated copper gasket, and 
is made in various sizes from 6 to 36 inches in diameter. 

Covering pipes. — Steam pipes should be covered, for the double 
purpose of saving the latent heat in the steam that would other- 
wise be lost in condensation, and also to prevent the engines from 
being damaged by this water of condensation. With coal at $3 
per ton, 10 feet of uncovered 6-inch pipe will cause an annual 
loss under average conditions of over $5 per year. A good cov- 
ering that would reduce this loss to $1 per year would only cost 
about $5. From this it will be seen that it pays to buy the best 



96 



STEAM POWER PLANTS. 




IS'<*' - — -- 



The Engineering RECORD. 
ELEVATION OF BOILER PIPING. 



i"Bo/fs. 



sU 



P ^r 



K-I"* 91"- *3^ 

The Enoineehcng REC 
DETAIL OF PIPE SUPPORT. 




METHOD OF CONNECTING DUPLICATE MAINS TO BOILERS. 

Figure 43.— Steam Piping Details at Great Northern Paper Co. 

SHEAFF AND JAASTED, ENGINEERS. 



STEAM POWER PLANTS. 97 

covering obtainable, and in making a selection the question of 
durability should be looked into fully as much as the efficiency 
of the covering when new. Sometimes the pipe covering is made 
part of the piping specifications, and again a contract is made for 
it with a manufacturer direct. The latter arrangement is much 
to be preferred. 

Specifications for piping. — When an engineer prepares accu- 
rate and complete scale drawings of the entire system of pipe- 
fittings, etc., the written specifications can be quite brief. They 
should call for bids on the engineer's drawings, name the lo- 
cality of the power house, give the time allowed to complete the 
work, and specify by name or make the following, if they are to 
be used, and are not marked on the drawings: Steam valves; 
water valves ; reducing valves ; back-pressure valves ; steam traps ; 
injectors; kind of packing used between the flanges; kind of pipe 
covering. The method of supporting pipes should be described, 
if it is not indicated in the drawings. The kind of fittings and 
pipe wanted should be clearly stated. 



Chapter VII. — Condensers. 



The purpose of attaching a condenser to a steam engine is to 
remove part of the pressure of the atmosphere, by creating a par- 
tial vacuum, from one side of the piston, and thus increasing the 
effective pressure acting upon the other side. If an engine is 
running without a condenser, with a mean effective pressure of 
40 pounds, and a condenser is added removing 12 pounds from 
the back pressure caused by the pressure of the atmosphere, the 
mean effective pressure would be increased, theoretically, to 52 
pounds, and the power would be correspondingly increased. If, 
however, the work done remains the same, the increased mean 
effective pressure, 52 pounds, can be reduced to 40 pounds by 
cutting off the steam earher in the stroke and thus save steam 
nearly in the proportion that the cut-off is reduced. A condenser 
can, therefore, either increase the capacity of an engine, or it will 
reduce its steam consumption per horse-power if the load and 
other conditions remain the same. If an engine is operated non- 
condensing with the most economical load for it and a condenser 
be fitted to the engine, this same load will no longer be the most 
economical one, although the steam consumption per horse-power 
per hour will probably be considerably less with the condenser 
than without it. A condensing engine should have a larger 
cylinder than a non-condensing engine to' do the same work, if 
both are to run with the lowest possible steam consumption per 
horse-power. The method of determining proper cylinder dimen- 
sions for engines running condensing and non-condensing was 
given in Chapter IV. 

A condenser provides means for bringing cool water into con- 
tact with exhaust steam or passing it through thin tubes around 
which the exhaust steam passes, so that the latter is condensed. 
A vacuum is formed in the condenser by reason of this conden- 
sation, and thus part of the pressure of the atmosphere is removed. 
Because of the small volume occupied by the condensed steam 
relative to its volume as steam at the same temperature, condensed 



V. 




^ Dscharge ', 



y-— Plan Waterside Station, New York Edison Company. 



STEAM POWER PLANTS. 99 

steam or water may be removed from the condenser by a com- 
paratively small pump using a small amount of power to operate 
it. This pump also removes such air as may be in the exhaust 
steam, hence it is usually called an air pump, although it serves 
to remove the water as well. 

Saving due to condensers. — Generally speaking, a condensing 
engine will use from 75 to 80 per cent, of the steam required by 
a non-condensing engine. Power, however, is required to drive 
the air pump, and this saving is, therefore, not a net gain. The 
steam required to drive an independent steam-driven air pump 
is from one to four per cent, of that used by the main engine, de- 
pending on the size of the latter. This use of steam for driving 
the air pump need not necessitate a loss, if the exhaust steam from 
the pump is used to warm the feed water before the latter is de- 
livered to the boilers. If the feed water is drawn from the air 
pump discharge or if it is fresh water heated in a feed water 
heater placed in the exhaust pipe between the engine and con- 
denser, no degrees Fahr. is about as high a feed temperature as 
can be obtained on account of the vacuum in the condenser and 
the correspondingly low temperature of the exhaust steam. It is, 
therefore, advantageous to use the steam exhausted by the air 
pump, for feed-water heating in an auxiliary heater, so called be- 
cause it receives the exhaust steam of the auxiliaries of the plant, 
such as the air and boiler feed pumps. This heater is sometimes 
called a secondary heater when a primary heater is placed in the 
exhaust pipe of the engine. By means of the auxiliary heater 
the feed water may be raised from no to about 170 degrees in a 
large well-proportioned plant, and to a greater extent in smaller 
plants, as the steam required for the air pump and boiler feed 
pump becomes a greater proportion of that used by the main en-, 
gine. If the feed water is drawn from a city supply or reservoir 
and is not passed through a heater in the exhaust pipe of an 
engine, the exhaust from an air pump and boiler feed pump will 
raise it to almost the same temperature that it would if the feed 
water was at a temperature of no degrees. 

With a non-condensing engine the feed water may be heated 
by the exhaust steam in a feed-water heater to within about 10 
degrees of the temperature of the steam or to about 205 degrees 
with steam at atmospheric pressure ; consequently, with condens- 
ing engines, the saving in coal used by the main engine due to a 

tofa 



100 STEAM POWER PLANTS. 

condenser over the use of the same engine running non-condens- 
ing is partly counterbalanced by the higher feed temperature that 
may be secured when running non-condensing. With feed water 
taken from the condenser discharge at a temperature of no de- 
grees, there would be a saving, vv^ith a steam pressure of lOO 
pounds, of about 9 per cent, if the feed water could be further 
raised in temperature to about 205 degrees, as it probably could 
be if the engine was run non-condensing. However, by using the 
exhaust steam from the air and boiler feed pumps of a condens- 
ing plant to warm the feed water taken from the air pump dis- 
charge, there will be such a small difference between the final 
feed temperatures in the two types of plants that the slight differ- 
ence can be neglected in considering the saving due to the use of 
a condenser. It is impossible, and perhaps unnecessary, to figure 
the exact saving a condenser will produce, but, generally speak- 
ing, it may be taken at about 20 per cent., hence plants are al- 
most always fitted with these auxiliaries when condensing water 
is to be had, and the exhaust steam is not needed for heating or 
for some manufacturing purpose. When an abundant supply of 
condensing water is not available, steam plant owners often go 
to considerable expense for artificial cooling devices, so great is 
the economy in using condensers. 

Types of condensers. — Condensers may be divided into three 
general types, known as the jet, the surface and the siphon con- 
densers. The jet and surface condensers require an air pump, 
and each of these may be again divided into direct-driven or in- 
dependent condensers, the former when their air pumps are 
driven by the main engine either by being directly connected to 
it or connected by a belt. The independent condensers are usually 
driven by steam cylinders forming part of their equipment. Con- 
densers with air pumps driven directly from the main engine have 
been almost abandoned for stationary engines, the satisfactory 
manner in which the independent condensers have been perfected 
and their superiority over the direct-driven condenser having 
brought this about. The greatest advantage of the independent 
air pump is its greater flexibility, it being possible to change the 
speed of the separately driven type without regard to the speed 
of the main engine, so that it can be run to suit any condition of 
load. 

The jet condenser usually consists of a pear-shaped chamber, 




Plate io.— Cross-Section Waterside St 



STEAM POWER PLANTS. 



101 



at the top of which the exhaust steam enters, while at one side is 
a connection for the injection or condensing water. The bottom 
of the chamber has a contracted neck connecting with an air 
pump which is sometimes very similar to the ordinary direct-act- 
ing steam pump, or, it may be an air pump of special design. A 
cross-section of the Worthington jet condenser with horizontal 
double-acting air pump is shown in Figure 44. 

The surface condenser consists of a shell, usually of cast iron, 
containing a large number of brass or copper pipes through which 
the condensing water is circulated, the exhaust steam being ad- 




Steam, 



Figure 44. — Jet Condenser. 



mitted to the shell in the space surrounding the pipes. The steam 
coming in contact with the cooled pipes is condensed, and the 
condenser is so connected with the air pump that the condensed 
steam flows by gravity to the air pump, by which it is removed 
to maintain the vacuum. If the cooling water is under pressure 
no pump is necessary to circulate it through the condenser. If 
not, a circulating pump is required and this may be driven by the 
same steam cylinder that operates the air pump. It is usually 
the practice to place the air and circulating pump and the steam 
cylinder operating them in line, tandem, beneath the condenser 



102 



STEAM POWER PLANTS. 



and on a base supporting the whole. An arrangement of this 
kind showing the Wheeler method of mounting a surface con- 
denser on the cylinders of a Knowles' air and circulating pump 
is shown in Figure 45. Circulating water is sometimes siippUed 
by centrifugal, pumps driven by an engine or electric motor. As 
the condensed steam does not come in contact with the circulating 
water in the surface condenser, this type can be used when the 
circulating water is of such a character that it should not be fed 
to the boilers. The condensed steam is used over again until it 
becomes so impregnated with cylinder oil from the engine that 




Figure 45. — Surface Condenser. 



it has to be replaced by fresh water. The presence of cylinder 
oil in feed water causes trouble in steam boilers, and it is the fear 
of this trouble from oil that prevents the wider adoption of the 
surface condenser in power plants. However, by providing 
proper filters of sand, cloth, sponges, excelsior or similar material 
for the feed water and properly looking after them there is no 
reason why the surface condenser cannot be used with success. 

The Bulkley siphon condenser, which in a general way is sim- 
ilar to others of this type, is shown in Figure 46. The steam 
from the engine is led in a pipe to the top of the condenser, which 



STEAM POWER PLANTS, 



103 



Mef Valvz. 



is elevated sufficiently to be placed about 34 feet above the sur- 
face of a hot well into which the condenser discharges. The in- 
jection water enters at the side and mingles with the steam at 
the lower edge of the cone shown. By contracting the neck of 
the condenser below the cone, sufficient velocity is given the 
water in falling to the hot well to maintain a siphon-like action 

that draws the steam from the 
exhaust pipe, and causes a vac- 
uum to exist in it. The injection 
water can be supplied by a pump 
of either the steam-driven or the 
centrifugal type. If the injec- 
tion water can be had under suf- 
ficient pressure, the pump is not 
necessary. This type of con- 
denser will lift water from a 
source of supply, such as a tank 
or reservoir, through a height 
of 18 feet or less, but with this 
arrangement the siphon must be 
started. This can be done by 
running a horizontal pipe from 
the reservoir or tank across to a 
tee in the vertical discharge pipe 
of the condenser. Water flowing 
through this and down the dis- 
charge will gradually exhaust 
the air from the upper part of 
the discharge pipe until sufficient 
vacuum is formed to draw the 
water up to the condenser and 
start the water flowing through 
it. When this is done a valve in 
the cross-connection or starting pipe is closed. 

Figure 47 shows an elevation of the Worthington central jet 
condenser which is a modification of the siphon type. It is called 
the central system because it is often used to condense the steam 
of more than one engine. An enlarged cross-section of upper 
part is shown in Figure 48. The condensing cone is considerably 
larger than in other siphon condensers, the idea being that the 




Figure 46. — Siphon Condenser. 



104 STEAM POWER PLANTS. 

steam and water are more thoroughly mixed, thus using less 
water. The spray is controlled by an adjustable nozzle. The 
neck of the condenser is not contracted, as it is in the ordinary 
siphon condenser, to give the high velocity to the descending 
water necessary to suck the air down into the discharge or tail 
pipe. The contracted neck was avoided to give the water an un- 
restricted fall so that it could not by any chance back up in the 
condenser and run over into the exhaust pipe. To assist in re- 
moving the air from the condenser cone an air pipe, shown in 
Figure 48, is led to a dry vacuum pump, which constantly re- 
moves air from this pipe and very considerably increases the 
vacuum over what would be obtained without it. The air cooler 
shown in the drawing is used to cool the air while it passes from 
the condenser cone to the vacuum pump, the air passing through 
tubes in the cooler around which the injection water is circulated. 
By cooling this air its volume is reduced, hence the vacuum pump 
has a little less work to do. 

Location of condensers. — It is important to locate a condenser 
of the jet or surface type on a lower level than the engine, so 
that the pipe connecting the engine and condenser will be either 
perfectly horizontal or pitch slightly toward the condenser. This 
is necessary to prevent the existence of a pocket where water can 
collect in the pipe line. As this pipe is under a vacuum, water 
due to condensation that collects in it cannot be drawn off by a 
trap. If a pocket does exist, there is chance, in the event of 
broken vacuum, of this water getting back into the cylinder and 
wrecking it. One occasionally sees a condenser located on the 
floor with an engine. When this is done the exhaust pipe from 
the engine drops from the bottom of the cylinder, then runs hori- 
zontally, then rises to the condenser, thus forming a pocket, to 
which objection has been raised; this arrangement should be 
avoided. 

There being a vacuum in the condenser, the injection water 
can be lifted from a reservoir or pond at a lower level. It is not 
advisable to lift water through a greater head than 20 feet, in- 
cluding the actual vertical distance the water is raised and also 
the friction of the water in the injection or suction pipe. A con- 
denser is sometimes located in a pit considerably below the engine 
in order that the lift may not be too great. As stated in the first 
chapter of this series, the availability of a supply of condensing 



STEAM POWER PLANTS. 



105 



water often determines the location of the power house. If a 
river or reservoir is nearby and it is not desirable to locate the 
power house close to the river, water can be led to a well close 
to the condenser either in an open trench or in a tunnel or conduit 



> Injection 



Plan. 




Afr Cooler. 



Cham for Spray 
Tail Pip&. 



*^ Eleva+ion 





Opening 1-oTaiJPip^,, 



Figure 47. — Central Jet Condenser. — Figure 48. 



and the injection pipe run to the well. This would overcome the 
use of a long injection pipe. If the injection pipe is run under- 
ground it should not be covered over with earth until after the 
condenser is started and the pipe tested for air leaks. One of the 



106 STEAM POV/ER PLANTS. 

most frequent causes of trouble with a condenser is a leaky suc- 
tion pipe, hence the greatest care should be used to make sure that 
it is perfectly tight. Various methods of connecting condensers 
with engines were given in the chapter on "Steam Piping." 

Water necessary for condensers. — A considerable amount of 
water must be available if a condenser be used, and to calculate 
this, one must first find the weight of water necessary to condense 
each pound of exhaust steam and then determine the amount 
necessary to condense all the steam exhausted by the engine. The 
former is found by dividing the rise in temperature that takes 
place in water used to condense the steam into the heat contained 
in one pound of steam at the pressure at which the exhaust valve 
in the engine begins to open less the heat in one pound of water 
at the temperature of the air pump discharge. Expressed alge- 
braically, this equation is: W^ (H — h) -^- (T — t) ; in which 
H is the total heat in steam at the terminal pressure, h is the heat 
in water at the temperature of the air pump discharge; T is the 
temperature of the discharge condensing water and t is the tem- 
perature of the entering condensing water. The value of H for 
different pressures and temperatures may be found in tables giv- 
ing the properties of saturated steam, and may usually be taken 
at 1,150. Taking average values for a surface condenser with h 
at 120, T at no, and t at 70, then W will be found to have a value 
of about 26 pounds per hour. If a jet condenser is used the con- 
densed steam and air pump discharge would have the same tem- 
perature. When the same water is used over and over again to 
condense with, as is done with cooling towers or cooling reser- 
voirs, the temperature of the condensing water is quite high when 
it enters the condenser, so that each pound can absorb a com- 
paratively small amount of heat, hence a correspondingly greater 
volume of condensing water is required. 

In estimating the quantity of injection water necessary, due 
consideration should be given the amount of steam exhausted by 
the engine during maximum load; also the increase in the steam 
consumption of the engine per horse-power that will occur when 
the engine has been in service for some time, due to the leakage 
of valves and piston on account of wear. The author believes 
in being very liberal in selecting condensers, for a good vacuum, 
particularly with engines operating with low mean effective press- 
ures, is conducive to high economy. Some engineers hold that a 



STEAM POWER PLANTS. 107 

high vacuum is a mistake, one of the reasons being that with it 
the temperature of the condenser discharge is lower and conse- 
quently the feed water will not be so hot. There is, however, a 
loss due to reducing the mean effective pressure acting on the 
engine piston that considerably more than offsets such a gain. 
By a decrease in the vacuum from 26 to 24 inches it would be im- 
possible to increase the feed water temperature more than 15 
degrees, and this would mean a saving of a httle more than i 
per cent. This decrease in vacuum in a compound engine, with 
125 pounds steam pressure, most economically loaded would 
effect, theoretically, an increase in the steam used of about 5 or 6 
per cent., and with a simple engine about 2.5 per cent. It will be 
noticed on investigating duty trials of large pumping engines 
where high duty is desired that a very high vacuum is sought by 
the builder. 

Sources of water supply for condensers. — Water for condens-. 
ing purposes may be obtained from rivers, in which event the 
water goes to waste after it is discharged from the condensers, or 
from ponds or artificial reservoirs. When drawn from ponds 
or artificial reservoirs the source of supply has to have sufficient 
volume and surface so that it will be cooled naturally by the air. 
If the reservoir is too small for this it must be cooled artificially 
by some method that exposes the water sufficiently to the air to 
cool it, as in the cooling tower. Reservoirs where the cooling is 
done naturally require surface sufficiently large to allow enough 
water to come in contact with the air to remove the necessary 
amount of heat from it, and they should also have sufficient vol- 
ume, if they are used continuously, so that the water can remain 
in the reservoir long enough to be cooled before being used again. 
Cooling reservoirs of this kind are rendered much more efficient 
by dividing them by partition walls so that the water is compelled 
to travel some distance in passing from the condenser discharge 
to the intake where it is drawn from the reservoir to return to 
the condenser. This is to prevent the discharge from the con- 
denser from immediately entering the intake, or short-circuiting, 
before it has time to cool. 

There is very little reliable information on the surface and vol- 
ume required in cooling reservoirs. Thomas Box, in his work on 
"Heat," says that when an engine works day and night the depth 
of the reservoir is unimportant, and that 210 square feet of sur- 



108 STEAM POWER PLANTS. 

face is required per horse-power. When an engine runs only 12 
hours per day the surface may be reduced to 105 square feet per 
horse-power, but in the latter case the depth of the reservoir 
must be such as to give 300 cubic feet per horse-power. Box 
assumes the use of one cubic foot or 62y2 pounds of water evapo- 
rated into steam per horse-power. These data are based on ex- 
periments when the water was reduced in temperature from 122 
degrees Fahr. to 82 degrees, the air being at a temperature of 52 
degrees and the humidity 85 per cent. 

Cooling towers. — These appliances provide means for artificially 
cooling condensing water, and their successful development has 
made it possible to obtain the benefit of a condenser in many 
plants where condensers would be out of the question without them. 
Usually they consist of large cylinders of sheet steel open at the 
top and enclosing either mats or tiles or some similar substance 
presenting a large surface over which the hot water from the con- 
densers is allowed to trickle downward, from distributing pipes 
at the top. The water falls into a reservoir at the bottom, from 
which it is returned to the condenser. An opening or openings 
in the side of the tower allow the air to enter and pass up 
through it, thus cooling the water. Usually a fan driven by an 
electric motor or small steam engine is used to stimulate this 
current of air. A cooHng tower can be located almost anywhere 
outside of a power-house, on the 'ground or on the roof. There 
is a loss of circulating water attending their use of from 10 to 15 
per cent, of that passing through them, owing to the evaporation 
that occurs. This, however, is more than made up, with jet con- 
densers, by the discharge from the air pump of the condensed 
steam. Where cooling towers are located at a higher eleva- 
tion than the engine, the condensing water must be pumped 
from the condenser to the tower, but the power required to do 
this is, with surface condensers, partly counterbalanced by the 
fall of water from the reservoir at the base of the tower to the 
condenser. The column of water in the condenser discharge pipe 
for the height of the tower itself is, of course, unbalanced. 

Proportioning condensers. — In the jet type of condenser the 
air pump has to remove from the condenser the injection water, 
the steam that is condensed, and a certain amount of air that finds 
its way into the exhaust steam either from the boiler or through 
leaks in the pipe, condenser, etc. The air is a very uncertain 



STEAM POWER PLANTS. 109 

quantity. With a surface condenser the cooHng water does not 
come into contact with the steam, hence the air pump has to re- 
move only the condensed steam and the air. To determine the 
size of the air pump for a jet condenser, the amount of injection 
water in pounds per minute necessary to condense the steam ex- 
hausted by the engine should be calculated in the manner pre- 
viously described, and this reduced to cubic inches per minute. 
This quantity should then be doubled, if the air pump is to be of 
the horizontal double-acting type — to allow for the air, and the 
number of cubic inches thus obtained should be about equivalent 
to the volume in cubic inches that should be displaced by the air- 
pump piston in one minute. This latter quantity, the displace- 
ment, is equal to the product of the area of the piston in square 
inches, the number of double strokes per minute and the length, 
of stroke in inches. 

With vertical single-acting air pumps the product of the area, 
of the cylinder in square inches and the length of stroke in inches 
and the number of double strokes per minute, should be 50 per 
cent, greater than the volume of injection water in cubic inches 
per minute. The size of air pump necessary to do a given amount 
of work can be determined with the data given, from the cata- 
logues of condenser manufacturers. These give the area of cylin- 
ders, length of stroke and maximum number of strokes that the 
air pump should run per minute. 

With surface condensers, the air-pump displacement should be 
20 times the volume of steam condensed, with horizontal double- 
acting air pumps, and 15 times the volume of steam condensed 
with vertical single-acting air pumps. Surface condensers usually 
have one square foot of surface in brass or copper tubes for every 
10 pounds of steam to be condensed per hour. 

Specifications for condensers. — Generally in purchasing jet con- 
densers, an engineer states the horse-power and type of engine 
for which a condenser is wanted, but it is better perhaps if the 
engineer is sure it will be correct, to give the number of pounds 
of steam that must be condensed in a given time, and the vacuum 
that is desired. This is usually 26 inches. If the engineer has 
calculated the volume of the air-pump cylinder, bids on conden- 
sers with air pumps of approximately this volume can be obtained. 
His specifications should also call for a blue print or drawinj^: 
showing the condenser the builder intends to supply, and on this 



110 STEAM POWER PLANTS. 

blue print should be given the outside dimensions of the con- 
denser, the size of the steam cylinder, the diameter and location 
of steam and exhaust pipe openings, the injection or suction pipe 
and the discharge pipe. The delivery and erection of the con- 
denser should be provided for, if the builder is to deliver and in- 
stall it. 

A specification for a surface condenser with combined air and 
circulating pumps should ask for a print of the apparatus, the 
size of the air, water and steam cylinders, the size of the steam 
and exhaust pipes, etc., also the square feet of heating surface 
in the condenser proper. 

Guarantees. — Sometimes a condenser manufacturer is required 
to guarantee its efficiency, but this is not often done. The form 
of guarantee that is fairest to the manufacturer would be, per- 
haps, to ask that the apparatus with an air pump piston speed 
not exceeding a specified amount, should condense a given amount 
of steam delivered to it at a certain pressure, and maintain a 
given vacuum, usually 26 inches, with a given temperature of 
cooling water. The location at which the vacuum is to be ob- 
tained should be stated, for frequently there is considerable drop 
in pressure between the exhaust pipe next to the engine and the 
condenser owing to a too long or too small exhaust pipe. The 
vacuum ought to be measured close to the condenser, for the 
maker of the latter is not responsible for the selection of the ex- 
haust pipe. He may not be responsible for the size and run of 
the injection pipe leading cold water to the condenser, or for the 
lift of water in it, and as these very materially afifect the efficiency 
of the condenser, the manufacturer should have the opportunity, 
if a guarantee is made, to approve the details, size and arrange- 
ment of the injection pipes. These remarks apply also to jet and 
siphon condensers. With a surface condenser and combined air 
and circulating pumps, the only guarantee that should be asked 
is maintaining a specified vacuiim with a piston speed of the air 
pump not exceeding a specified amount and a specified tempera- 
ture of cooling water. The manufacturer would have to satisfy 
himself with the arrangement of the water piping that it was pro- 
posed to use. If a- complete cooling tower and condensing outfit 
was to be supplied the guarantee should state the vacuum that is 
to be obtained with a given temperature of outside air, and when 
that air contains a certain percentage of moisture. 



Chapter VIIL — Feed Water Heaters and Economizers. 

Value of feed-water heaters. — Exhaust-steam feed-water heat- 
ers are used to heat the water fed to boilers with steam exhausted 
by engines and pumps, and the saving due to their use is so great 
that plants are seldom constructed without them. Generally 
speaking, for every ii degrees that feed water is warmed there 
is a saving of i per cent, in .he fuel burned. With sufficient ex- 
haust steam available, cold feed water at 70 degrees Fahrenheit 
can be raised in temperature to 200 degrees, thus saving nearly 
12 per cent, of the fuel. The heater will in many locations, there- 
fore, reduce the fuel consumption enough to pay for itself in a 
few months, the exact time depending upon the cost of the 
fuel. 

Types of heaters. — Exhaust-steam feed-water heaters are of 
two types, the open and the closed. In the former, the heater con- 
sists of a box-like receptacle of cast-iron or boiler steel to which 
the exhaust steam is led so as to fill its interior. The cold feed 
water is admitted at the top and in most designs trickles to the 
bottom over a series of trays and is thus brought in contact with 
the steam and is heated by it. If the water contains scale-form- 
ing salts which are precipitated at temperatures below 200 de- 
grees, they collect on the trays, which are removable for clean- 
ing. This type of heater sometimes has a filter in its base for 
further removing these precipitated salts and impurities that can 
be intercepted by filtration. The feed water is drawn from the 
bottom of the heater and pumped to the boilers. The pump must 
be located so as to receive the water under pressure, as it will not 
lift the water if it is under a high temperature. The condensa- 
tion from heating systems, the discharge from traps connected 
to high-pressure drips, engine jackets, reheaters, etc., which are 
to be returned to the boilers, can be connected to a heater of 
this type. A certain water level is maintained in the heater, and 
to do this the supply of cold feed water is controlled by a valve 
operated by a float in the heater, so that cold water is admitted 



112 STEAM POWER PLANTS. 

when the boiler feed pump draws water from it faster than it is 
suppHed by the heating returns, drips, etc. It is absolutely essen- 
tial that an efficient grease separator be placed in the steam pipe 
leading to an open heater, so that oil cannot enter it and pass on 
to the boilers mixed with the feed water. 

Closed heaters usually consist of a cylindrical shell of cast-iron 
or boiler steel containing tubes extending from one head to the 
other, or coils of pipe. Sometimes the exhaust steam is admitted 
to the shell so as to surround the pipes or coils containing the 
feed water, in w^hich event the heater is said to be of the water- 
tube type. If the steam is inside of the coils with the water sur- 
rounding them, it is a steam-tube heater. Closed feed-water heat- 
ers are usually supplied with a steam, inlet and outlet, although 
they are sometimes arranged with only a single connection, re- 
liance being placed on the vacuum that forms in the heater when 
steam is condensed to cause more steam to flow into it. As a 
certain amount of air exists in the exhaust steam, this will find 
its way into the heater and is apt to impair its efficiency. For 
that reason many engineers believe that there should be a double 
steam connection, unless some means of removing the air is pro- 
vided, to prevent air from accumulating and thus to insure a 
thorough circulation of steam through the heater. Experience 
has shown in water-tube heaters that the best results are obtained 
when the water is compelled to pass through the tubes succes- 
sively for the reason that the velocity of the water per unit of 
heating surface is greater. Closed heaters are made to rest in a 
horizontal or vertical position. The latter are to be preferred 
if it is convenient to use them as they take up much less floor area 
and the circulation of water in them is much more thorough un- 
less the tubes are subdivided into groups. 

Uses for heaters. — The manner in which feed-water heaters are 
used depends upon the type of plant in which they are installed. 
With non-condensing engines, where the exhaust steam is avail- 
able for feed-water heating, the feed water may be raised to a 
temperature of about 205 degrees Fahrenheit; and when this is 
done, it is usually the custom to allow one square foot of heating 
surface in brass or copper pipes for every 90 pounds of water 
passed through the heater per hour. With condensing engines it 
is sometimes the practice to place a feed-water heater of the 
closed type in the exhaust pipe of the engine, unless two different 



I ^Main Steami \header 12" 




m 



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Discharge Main from Condensers. Condenser 
^ Pumps. . 

Longitudinol Section. 




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Longitudinal Section. 



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Plate ii. — Power Station', Capital Traction Company, Washington, D. C. 



STEAM POWER PLANTS. 113 

sets of conditions exist. If the air pumps and boiler-feed pumps 
are steam driven, and the steam exhausted by them added to the 
steam exhausted by all other pumps or steam auxiliaries in the 
plant amounts to one-seventh or more of the steam generated in 
the boilers, this exhaust steam from the auxiliaries can be led to 
an auxiliary feed-water heater and the feed water warmed by it 
from about 75 to about 205 degrees. In this event, a heater in 
the exhaust pipe of the engine would be of no value ; nor would 
it, if the feed water were drawn from the condenser discharge, 
for in that event it would be at nearly as high a temperature as 
the exhaust steam from the main engine, so that it would hardly 
pay to attempt to use this steam for heating. The exhaust steam 
from the main engine being under a partial vacuum., say 26 inches, 
would have a temperature of about 125 degrees, and the con- 
denser discharge probably about 100 degrees. If the exhaust 
steam from the auxiliaries be not sufficient in quantity to raise the 
feed water from a temperature of 60 or 70 degrees to about 205 
degrees, then a feed-water heater can be placed in the exhaust 
pipe of the engine and the water warmed from the lower temper- 
ature to about 115 degrees and finally passed through an aux- 
iliary heater and there warmed to as high a temperature as pos- 
sible with the auxiliary exhaust steam available. This auxiliary 
heater is almost invariably used in the latest plants while only 
occasionally is a heater placed in the main exhaust pipe of a 
condensing engine. Auxiliary heaters of the closed type should 
have the same amount of heating surface as heaters receiving 
steam at atmospheric pressure. This rating was previously given. 
Heaters placed in the exhaust pipes of condensing engines should 
have more surface, usually one square foot for every 60 pounds 
of water passed through the heater per hour, this being necessary 
because the difference between the temperature of the steam and 
the mean water temperature is less than it is with heaters using 
steam at atmospheric pressure. _ 

Condensation in heaters. — The condensation that occurs in a 
feed-water heater amounts to about one-seventh of the weight of 
the feed water passing through the heater, when the water is 
raised from 70 to about 205 degrees. In an open heater this, of 
course, mingles with the feed water and passes on to the boilers 
with it. In a closed heater, the steam not being in contact with 
the water, the condensation occurring: has to be removed from 



114 STEAM POWER PLANTS. 

the heater, and this can be done by leading it to a steam trap. 
It should not be forgotten that the steam pressure in a heater is 
frequently at practically the same pressure as the atmosphere, 
hence the discharge from the trap should be carried downward, 
or on a level rather than upward, as there is no pressure to lift 
the water. It is not necessary to save the condensation in a closed 
heater unless the cost of this water which, as has been said, is 
about one-seventh of the total feed water, is sufficient to make the 
saving of it advisable; or unless there is not enough exhaust 
steam to warm the feed water to as high a temperature as may 
be possible. If there is plenty of exhaust steam, that would 
otherwise go to waste, available for heating, the heat in this con- 
densation in the heater is of no value. If the condensation from 
a closed feed-water heater is to be returned to the boilers, it 
should be trapped, and the discharge from the trap led to a re- 
ceiving tank combined with a pump controlled by the level of the 
water in the tank. Other drips from cylinder jackets, high-press- 
ure steam pipes, reheating receivers, etc., caru also be led to this 
tank, each discharging through a trap, or the condensation can 
be returned to the boilers direct by the steam loop or the Holly 
system. 

Purchasing heaters. — In purchasing a feed-water heater for a 
power plant for a manufacturing or electric company, the heater 
is usually purchased by the owner direct, although in some plants, 
notably those in office buildings, the purchase, delivery and in- 
stallation of the feed-water heater is frequently included in the 
specifications for the piping. The writer believes that it is much 
better to make the purchase of the heater a separate contract. 
The specifications for a closed heater should state the amount of 
heating surface required, the kind of metal that the tubes are to 
be made of, whether it is to be of the steam or water-tube type, 
and horizontal or vertical. If the supplying and installation of 
the heater is to be made part of the contract for the steam piping 
or some other part of the plant, the contractor undertaking it 
should be required to deliver and erect it. If the heater is to be 
purchased direct from its manufacturers, the specifications should 
ask that the bids cover the delivery of the heater free on board 
cars at the nearest railway point to the power plant. The specifi- 
cations should ask each bidder to furnish a blue print or drawing 
showing the details of the construction of the heater it is pro- 



.^9,se i 




Plate 12. — Power Plant, Pittsburg and Lj^ke Eric Railroad, Pittsburg, Pa. 



STEAM POWER PLANTS. 115 

posed to furnish, its exact dimensions and the location of the 
steam and water outlets and their sizes. 

There is no general rule that the writer is aware of for pro- 
portioning heaters of the open type. Therefore a specification 
for a heater of this kind should state the quantity of water to be 
passed through the heater in a given time and also the initial 
temperature of the water and the final temperature desired. A 
print or drawing of the heater a bidder is to provide should be 
obtained and the inside dimensions of the heater, the volume of 
the steam and water space, etc., should be investigated. The 
heater must not be too small, otherwise the water in passing 
through it cannot be broken up in sufficiently small particles to 
allow the water to mix thoroughly with the steam and thus be 
sufficiently heated by it. If a guarantee as to the efficiency of a 
feed-water heater is required, it should be in the following form : 

The maker guarantees the heater to be capable of warming 

pounds of water per hour from a temperature of degrees, 

Fahrenheit, to degrees Fahrenheit with sufficient steam at 

atmospheric pressure. 

Economizers. — Economizers are used in connection with steam 
boilers to warm water either for boiler feeding or for some man- 
ufacturing purpose, by the heat in the gases from boilers that 
would otherwise go to waste. Economizers are also useful in 
increasing the capacity of a boiler plant already in operation, in 
providing means for storing a large quantity of water at high 
temperatures, which is of advantage in the event of a sudden in- 
crease in the demand for steam. They also deliver the water to 
boilers at high temperature and reduce strains in boilers due to 
the admission of cold water. One disadvantage of economizers 
is that they reduce the draft slightly owing to the friction of the 
gases passing through them and to the reduction in temperature 
of the gases. Provision should be made for this by the use of 
mechanical draft or of larger chimneys than would be necessary 
if economizers are not used. In plants already constructed the 
addition of economizers reduces the coal consumption, and this 
counterbalances in a measure the loss in draft, as less draft is 
necessary with them because less fuel is burned. 

Economizers consist of vertical cast-iron pipes about 4 inches 
in diameter and 9 feet long placed in rows several inches apart, 
each row being connected at the top and bottom to cast-iron head- 



116 



STEAM POWER PLANTS. 



ers through which the water is suppHed and withdrawn. They 
are provided with scrapers that encircle the pipes and that are 
continuously raised and lowered by a suitable mechanism, the 
power coming usually from a small steam engine. Economizers 
are placed in brick flues between the boilers and the chimney, and 




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Figure 49.— Economizer Arrangement, Plant of Schwarzchild 
Sulzberger, Chicago, III. 

L. LEVY, CHIEF ENGINEER. 



a by-pass flue must be provided for use when the economizer is 
out of service, either for cleaning, which is necessary at intervals, 
or for repairs. Economizers are used to a very considerable ex- 
tent in Europe, more so in fact than in the United States, where 



STEAM POWER PLANTS. 117 

engineers are now, however, rapidly appreciating their advan- 
tages. When first introduced, a number of failures occurred 
mainly due to improper design. They were then either con- 
structed of poor materials improperly put together or there was a 
lack of sufficient heating surface necessary to make the saving 
that they should produce. Since the economizer has been per- 
fected and made of durable materials, their advantages have be- 
come recognized. 

The heating surface in economizers takes the place, in a meas- 
ure, of additional boiler-heating surface. If a boiler is operating 
under certain conditions so that, with a certain rate of evapora- 
tion per square foot of heating surface, a certain temperature of 
waste gases follows, it vv^ould be possible to add more heating sur- 
face and abstract more heat from these gases ; but the boiler heat- 
ing surface would not be so efficient in doing this as an equivalent 
amount of economizer surface, for the reason that the average 
temperature of the water in the economizer is lower than that of 
the water in the boiler ; this causes a more rapid transfer of heat 
from the gases to the water in the economizers than there would 
be from the gases to the water in the boiler. The saving that an 
economizer can produce increases as the flue temperature in- 
creases because there is more heat for it to absorb. An economizer 
can only heat the water to a given point, hence as the temperature 
of the entering water increases, due to previous heating, as in an 
exhaust steam heater, the saving possible with the economizer 
becomes less. If the ratio of boiler heating surface to the amount 
of coal burned is such that as much of the heat in the waste gases 
is absorbed as is possible, there is not as much heat left in the 
gases for the economizers to save as there would be if the ratio 
of boiler heating surface to the amount of coal burned were less. 
Barrus, in his book on "Boiler Tests," states in effect that where 
a boiler is operated most efficiently, the temperature of the waste 
gases should not exceed about 400 degrees Fahrenheit, and boil- 
ers are usually so proportioned that about this temperature exists 
when the highest efficiency is attained. Owing, however, to the 
accumulation of soot upon the boiler surface or to running at a 
higher rate of evaporation than the normal, the temperature of 
the waste gases usually exceeds that given so that an economizer 
is valuable in even a well proportioned boiler plant. Mr. Barrus 
gives some excellent data showing the saving made by economiz- 



118 STEAM POWER PLANTS. 

ers with low temperatures of flue gases, and they are reproduced 
in Table I, herewith: 

Table I. — Babeus' Tests of Economizers. 

Heating surface, boiler, sq. ft 1,894 1,058 5,592 3,126 

Heating surface, economizer, sq. ft i,600 1,920 1,280 1,600 

Temperature of gases leaving boiler, deg 376 361 403 435 

Temperature of gases leaving economizer, deg 231 254 299 279 

Temperature of feed water entering economizer, deg. 95 79 111 84 

Temperature of feed water entering boiler, deg 175 145 169 196 

Increased evaporation produced by economizer, per 

cent 10.5 7 9.3 12.8 

Mr. William R. Roney in a paper on "Mechanical Draft" 
(Transactions, Am. Soc. M. E., Vol. XV), gives some additional 
data on the saving due to economizers working under various 
conditions in nine different plants. They are given in Table II. 

Table II. — Roney's Tests of Economizers. 

Plants tested. .'. 1 2 3 4 5 6 7 8 9 

Gases entering economizer, deg 610 505 550 522 505 465 490 495 595 

Gases leaving economizer, deg 340 212 205 320 320 250 290 190 299 

Water entering economizer, deg 110 84 185 155 190 180 165 155 130 

Water leaving economizer, deg 287 276 305 300 300 295 280 320 311 

Gain in temperature of water, deg. .. 117 192 120 145 110 115 115 165 181 

Fuel saving, per cent 16.7 17.1 11.7 13.8 10.7 11.2 11.0 15.5 16.8 

In considering the saving that an economizer produces it is 
necessary to take into account the interest on the investment and 
the cost of repairs, cleaning, etc. Economizers cost, it is said, 
about $5.40 per boiler horse-power for plants of 1,000 boiler 
horse-power or over, on the basis of 4.8 square feet of economizer 
surface per boiler horse-power. This includes the cost of the 
brick setting, delivering and erecting, etc. Three per cent, of the 
investment will probably do more than pay for the cost of the 
operation, cleaning and repairs. Assume a 1,000-horse-power 
boiler plant to operate 300 ten-hour days per year, that the coal 
consumption is 3^ pounds per boiler horse-power per hour and 
that coal costs $3 per ton of 2,000 pounds delivered. The annual 
fuel cost would then be $15,750, and if an economizer reduced 
this by 12 per cent., then the saving that an economizer would 
produce would be $1,890. The cost of the economizer at $5.40 
per boiler horse-power would be $5,400 and 8 per cent, of this 
for interest, repairs, operating and cleaning is $432. Deducting 
$432 from $1,890 would leave a net saving of $1,458, which is 
sufficient to pay for the economizer in less than four years. If 



STEAM POWER PLANTS. 119 

the plant was operated continuously, the annual fuel cost would 
be $45,990, and the net saving $5,085, sufficient to pay for the 
economizer in about one year. The 12 per cent, that was assumed 
in the previous calculations is a conservative estimate for the sav- 
ing with a low temperature of feed water. In the four tests made 
by Mr. Barrus, previously noted, the average saving was 9.9 per 
cent, and this was obtained with unusually low temperatures of 
the escaping gases, due partly to the low-steam pressure under 
which the plants were operated, these varying in the different tests 
from 68 to 82 pounds. Economizer makers will guarantee that 
they can produce a saving of 6^ per cent, when the temperature 
of the water entering them is as high as 200 degrees, the econo- 
mizers having 4.5 square feet of heating surface per boiler horse- 
power and the boilers working at their normal rating. 



Chapter IX. — Mechanical Draft. 

Theory of combustion. — As pointed out in a previous chapter, 
there are two independent factors that effect the efficiency of a 
steam boiler. One is the efficiency of the heating surface or its 
abihty to transmit to the water the heat to which it is exposed, 
and the other is the efficiency of the furnace, by which is meant 
the amount of heat actually contained in each unit volume of fur- 
nace gas compared to that theoretically possible of attainment. 
A high surface efficiency demands that the temperature of the 
gases in contact with the boiler be as high as possible, for the rate 
of heat transfer is some function of the difference in temperature 
of the water and gases, and the greater the difference the more 
heat per unit of surface will be transmitted. A high furnace effi- 
ciency demands that just the proper amount of air be supplied to 
the furnace per pound of fuel burned. Too little air, due to a too 
thick bed of fuel on the grate in proportion to the available draft, 
results in loss due to the incomplete combustion of the fuel, part 
of the carbon being burned only to carbonic oxide instead of to 
carbonic acid, as it should if the combustion is complete. Too 
much air, on the other hand, due to too thin a bed of fuel, lowers 
the temperature of the furnace gases and thereby decreases the 
heat transferred per unit of heating surface, owing to the smaller 
difference between the gas and the water temperatures ; it also 
increases the volume of gases and this in turn necessarily in- 
creases the velocity of their flow through the passages of the 
boiler, thus giving less time for their heat to be absorbed. 

A thin fire allows an excess of air to enter the furnace, while 
a thick fire tends to reduce it on account of the greater resistance 
offered. Mr. Walter B. Snow writes as follows in explaining 
the higher efficiency of a high rate of combustion : 'Tf the size 
of a grate is reduced but the same amount of fuel burned by 
increasing the rate of combustion, the diminished area of the 
grate and of the exposed interstices between the fuel necessitates 
a higher velocity to secure the admission of a given v^olume of 



STEAM POWER PLANTS. 121 

air. This increased velocity in turn requires greater draft or air 
pressure. The volume at any given temperature passing through 
the coal is proportional to the velocity, but the pressure varies as 
the square of the velocity. Therefore, if a given grate be reduced 
one-half and the rate of combustion doubled, so as to maintain the 
same total consumption, the same volume of air would have to 
travel through the exposed interstices at twice the velocity. But 
the pressure or vacuum would be four times as great, and, as a 
consequence, the air would be forced or drawn into spaces be- 
tween the fuel which it could not reach under lesser impelling 
force. Much more intimate contact and distribution are the re- 
sults. Less free oxygen passes through the fuel bed unconsumed, 
and for a given supply of air a higher efficiency of the fuel is at- 
tained.^' Most leading authorities unite in the belief that a higher 
efficiency is secured in steam boilers when operating at compara- 
tively high rates of combustion. It is advisable to provide for 
this in plants using coal that can be burned rapidly, care being 
taken at the same time to provide sufficient draft to run the boil- 
ers over their normal rating when occasion demands. Certain 
coals high in ash and in sulphur cannot be burned at more than 
ordinary rates for reasons explained in Chapter II in the section 
relating to coals. 

Necessity for ample draft. — Means for providing a strong 
draft for steam boilers is one of the most essential features of a 
plant, for if sufficient coal can be burned a boiler will generate 
steam several times as rapidly as under normal conditions. This 
means that a smaller number of the boilers can be relied upon to 
furnish the steam required, while others are shut down for re- 
pairs or cleaning, than would be needed if less draft was avail- 
able. The investment for boilers, therefore, need not be so great. 
Of course, when making steam at abnormally high rates of evapo- 
ration, the efficiency is not so good as under the conditions of 
normal working, but it is cheaper to allow some fuel to go to 
waste occasionally than to spend more money in the first place 
for boilers only used at long intervals. More complaints with 
steam boilers are probably traceable to insufficient draft than to 
any other cause. Draft is secured by a chimney, by mechanical 
draft produced by fans, or by steam jet blowers. 

Mechanical draft. — Mechanical draft may be secured by two 
methods, known as induced draft and forced draft. In the former, 



122 STEAM POWER PLANTS, 

a fan is connected with the smoke flue from a boiler or batteries 
of boilers, so as to suck the gases through the furnace, gas pas- 
sages and flues to the fan, which discharges it usually through a 
short chimney, but sometimes through a high one. Forced draft is 
the term applied to that system where air is forced into the furnace 
beneath the grate bars, either by a fan or by a steam, jet blower. 
If mechanical draft is to be used, induced draft is usually installed 
in new plants. Forced draft with a fan is sometimes provided 
for in new plants, but more often in old plants, as it is sometimes 
easier to install than the induced system. The objection to forced 
draft lies in the fact that a pressure greater than that of the at- 
mosphere is created in the furnace and gas passages which may 
cause the gas to pass outward through cracks in the setting of 
boilers and through the fire doors when the fires are being re- 
plenished or cleaned. Dampers in the blast pipe and uptake, to 
be closed when the fire doors are opened, may Overcome this latter 
objection. With induced draft the leakage through the doors and 
brickwork is of course inward. 

Steam jet blowers can only produce a moderate draft. Their 
steam is believed to be useful in preventing clinker from forming 
on the grates with certain kinds of anthracite coals. Steam jets 
are used to a considerable, but decreasing, extent in the anthracite 
coal regions. Experiments made by a Board of Steam Engineers 
of the Navy Department with five diflferent types of steam jets 
showed that they used from 8.3 to 21.2 per cent, of the steam 
generated in the boiler to which the jets were applied. Draft can 
be obtained from fans with only a fractional part of these 
amounts. Under ordinary conditions a fan for mechanical draft 
can be driven by from i to 5 per cent, of the steam evaporated 
in the boilers operating under ordinary conditions, depending 
upon the size of the plant. 

Advantages of mechanical draft. — Draft produced by fans 
possesses many advantages over chimneys as ordinarily propor- 
tioned. Probably the greatest of these is its flexibility, it being 
possible to regulate the speed of the fan so that the proper rate 
of combustion for the amount of steam required is maintained 
entirely independent of the weather conditions ; another important 
advantage is the ability of the fans to create a much greater draft 
than is possible with a chimney. Steam engines for driving fans 
are frequently fitted with valves arranged to govern the speed of 



STEAM POWER PLANTS. 



123 



the engine according as the boiler pressure varies, increasing it 
as the pressure falls and reducing it as it rises above the normal. 
Mechanical draft enables economizers to be placed in the flue and 
reduce the temperature of the escaping gases by heating the feed- 
water far below, the temperature that is necessary in a chimney 



9xmiM >i„'jjm m*7!B7, 




ngrfn 



. ENaiiiciniHO RECORD 



Figure 50. — Power House, Olympia Mills, Columbia, S. C 

W. B. SMITII-WHALEY, ENGINEER. 



to create a draft. The reduction in draft due to the use of econ- 
omizers is a much greater percentage of the available draft with 
a chimney than it is of the draft where fans are employed. Again, 
the greater draft of fans enables cheap low-grade fuels to be 
burned that could not easily be used with the chimney draft, and 



124 STEAM POWER PLANTS. 

the saving that these fuels brings about in some locaHties is a very 
considerable sum of money. Still another point in favor of me- 
chanical draft lies in the portability of the fans in case a change of 
location is desired. 

Theory of fans. — Before explaining the method of selecting 
a fan for a given service it is necessary to consider briefly their 
theory of operation. Fans for mechanical draft are invariably 
of the centrifugal type and consist of a paddle wheel revolving 
in a sheet iron casing, the air entering an opening in the casing 
at the axis of the wheel and being propelled radially to the casing 
by the action of centrifugal force, finally escaping by an outlet 
provided. The velocity with which the air is moved is expressed 
by the well-known formula : 

v = i/ 2g h, (1) 

in which v equals the velocity and h equals the head due to the 
velocity and also to the pressure divided by the density. There- 
fore, 

v^^ {2gp~-d). (2) 

The work done in moving this air is equal to the product of the 
velocity of the air in feet per second, the pressure in pounds per 
square foot and the effective area in square feet over which this 
pressure is exerted. If W represents the work done, p the pres- 
sure in pounds per square foot, a the area in square feet and v 
the velocity in feet per second, then : 

W=pav. (3) 

From (2) we have, by squaring and transposing: 

p=:dv'^-^2g. (4) 

and substituting its value in (3) we have: 

W^=dav^ -^ 2g. (5) 

From this it will be seen that the power required to drive a fan 
varies as the cube of the velocity. In other words, if the velocity 
is dorbled the power required will be eight-fold ; if tripled, 27- 
fold. As the velocity of the air is practically the same as the peri- 
pheral speed of the fan it will be seen how essential it is to use a 
large fan at its proper speed rather than a small fan running at a 
higher speed than is necessary to obtain the desired pressure, and 
thus the desired volume. The pressure varies as the square or 
the speed, as shown in formula (4), hence the pressure is quad- 
rupled by doubling the speed. 



i 



STEAM POWER PLANTS. 



125 



Design of fans.— From the work upon ''Mechanical Draft" 
by Mr. Walter B. Snow, published by the B. F. Sturtevant Com- 
pany, the following quotations relating to the design of fans have 
been taken : 

"In the design of a wheel to meet given requirements, it is 
necessary to make its peripheral speed such as to create the de- 
sired pressure, and then so proportion its width as to provide for 
the required air volume. Evidently the velocity and correspond- 
ing pressure may be obtained either with a small wheel running 
at high speed or a large wheel running at low speed. But if the 
diameter of the wheel be taken too small, it may be impossible 




Figure 51. — Cross-Section, Power House, Olympia Mills. 



to adopt a width, within reasonable limits, which will permit of 
the passage of the necessary amount of air under the desired 
pressure. Under this condition it will be necessary to run the 
fan at higher speed in order to obtain the desired volume. But 
this results in raising the pressure above that desired, and in un- 
necessarily increasing the power required. On the other hand, 
if the wheel be made of excessive diameter it will become almost 
impracticable on account of its narrowness. Between these two 
extremes a diameter must be intelligently adopted which will give 
the best proportions. 



126 STEAM POWER PLANTS. 

"It has been determined experimentally that a peripheral dis- 
charge fr.n, if enclosed in a case, has the ability, if driven to a cer- 
tain speed, to maintain the pressure corresponding to its tip 
velocity over an effective area which is usualty denominated the 
'square inches of blast.' This area is the limit of its capacity 
to maintain the given pressure. If it be increased the pressure 
will be reduced, but if decreased the pressure will remain the 
same. As fan housings are usually constructed, this area is con- 
siderably less than that of either the regular inlet or outlet. 

"The square inches of blast, or, as it may be termed, the capacity 
area of a cased fan, may be approximately expressed by the em- 
pirical formula: 

Capacity area = DW -^ X. 

In which D = diameter of fan wheel in inches. 

W = width of fan wheel at circumference in inches. 
X = a constant dependent upon the type of fan and 
casing. 

"An approximate value for X for Sturtevant fans for general 
practice is not far from 3, but this is to be used only to determine 
the capacity area over which the given pressure may be main- 
tained. This is not a measure of the area of the casing outlet, 
which is always larger than the square inches of blast. As a 
consequence, the pressure is lower and the volume discharged is 
somewhat greater than would result through an outlet having 
the square inches of blast for its area. But the maximum press- 
ure may be realized when the sum of resistances is equivalent to 
a reduction of effective outlet area to that of square inches of blast. 
The volume of air which, under the given pressure, will flow 
through the given capacity area, and hence the volumetric capacity 
of the fan under the given conditions, may be determined from 
Table I. In a similar manner the horse-power may be ascertained, 
the proper efficiency coefficient being applied. 

"Both the volume and the power required will evidently in- 
crease with the area of the outlet, being greater with the normal 
outlet than with that representing the capacity area. But this in- 
crease will not be proportional to the area, for the pressure and 
consequently the velocity will be lower with the larger area. The 
greatest delivery of air and the largest consumption of power will 
occur when the casing is entirely removed and the fan left free to 
discharge entirely around its periphery. 




r r— 1 II 1 ^„ .» „; iy » ' ' 

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>tATloii, BosTox, Mam. 

•• • CO.. KllO'a* AKO coxt'b 



STEAM POWER PLANTS. 127 

"If volume alone regardless of pressure is the requisite, the 
larger the fan the less the power required. There is a strong 
temptation, however, for a purchaser to buy a smaller fan and 
run it at a higher speed ; for he sees only the first cost and does 
not realize the entailed expenditure for extra power. If possible 
a fan should never be made so -small that it is necessary to run 
it above the required pressure in order to deliver the necessary 
volume. To double the volume under such circumstances re- 
quires eight times the power; three times the volume demands 
twenty-seven times the power. 

"When a fan is employed for exhausting hot air or gases, the 
speed required to maintain a given pressure difference is evidently 
greater than that necessary when cold air is handled, the differ- 
ence being due to, and inversely proportional to, the absolute 
temperature." 

With forced draft it will be safe to assume that 300 cubic feet 
of air are supplied per pound of coal burned, and with induced 
draft 300 cubic feet supplied but 600 cubic feet exhausted by the 
fan if the gases are to be at a temperature of about 500 degrees 
Fahrenheit or 450 cubic feet exhausted if at 300 degrees temper- 
ature, as might be expected with economizers. With induced 
draft the fan has to handle hot gases of approximately double the 
volume that it would if the fan was supplying air to the grates. 
As the gases are lighter, however, the power required per cubic 
foot of gas removed is less than it is per cubic foot of air with 
forced draft. Knowing the amount of coal burned under ordinary 
conditions, say four pounds per boiler horse-power per hour, the 
amount of air required per minute can be determined. The press- 
ures usually required in forced draft vary from ^ to i ounce per 
square inch and in induced draft from >4 to ^ ounce, depending 
on the fineness of fuel, the readiness with which it burns, the 
length of flues and number of bends in them, etc. 

Tables I and II are taken from "Mechanical Draft," before 
mentioned. In the former is given the volume of air in cubic 
feet for various pressures which may be discharged in one minute 
through an orifice having an effective area of discharge of one 
square inch, or per square inch of blast. The method of using 
these tables can best be explained, perhaps, by working out a 
typical case. Suppose we are to design an induced-draft fan to 
handle the gases from 1,000 horse-power of boilers against a 



128 



STEAM POWER PLANTS. 



pressure of ^ ounce. At 4 pounds of coal per horse-power per 
hour and 600 cubic feet of gas per pound, 40,000 cubic feet of gas 
would have to be exhausted per minute. Opposite 34 ounce press- 
ure in Table I, it will be seen that a fan will supply 31.06 cubic 
feet, say 31 cubic feet, per square inch of blast. Dividing 40,000 
by 31 would give 1,290 as the number of square inches of blast 
the fan would require. But the square inches of blast equal 
DW-^3. In standard fans of the Sturtevant make W is ap- 
proximately equal to D -f- 2.4, therefore : 

Square inches of blast = D^ -^- 7.2. 
Substituting 1,290 for the square inches of blast we have: 1,290 
== D^ -f- y.2, from which D equals 96 inches or 8 feet for the diam- 
eter of the fan. 

To determine the velocity at which the fan should be run, 
reference should be made to Table 11. For the column corre- 
sponding to ^ ounce it will be seen that an 8-foot fan should 
run at 178 revolutions per minute to give the capacity required. 
By increasing the speed at times of overload the pressure and 
volume of gases can be increased. 



TABLE I.— VOLUME OF AIR DISCHARGED AND 
QUIRED WHEN AIR UNDER GIVEN PRESSURE 
CAPE INTO THE ATMOSPHERE. 

a <x> 



3 (u la 

m a . 

«-i O 50 

P-i 



% 

IS 



Volume of air discharged tlirough 
an orifice of an effective area of 
discharge of 1 sq. in. (or per 
square inch of blast). 

17.95 cubic feet per minute. 

21.98 

25.37 

28.36 

31.06 

33.54 

35.85 

38.01 

40.06 

42.0 

43.86 



HORSE-POWER RE- 
IS ALLOWED TO ES- 

Horse-power re- 
quired to move 
the given vol- 
umes of air un- 
der given con- 
ditions of dis- 
charge. 

0.00122 
0.00225 
0.00346 
0.00483 
0.00635 
0.00800 
0.00978 
0.01166 
0.01366 
0.01577 
0.01794 



In the last column of Table I is given the horse-power requird 
per square inch of blast to move given quantities of air, under 
different pressures and at a temperature of 50 degrees Fahr. For 
forced draft these quantities can be used directly, but it should 
be remembered that they refer to the theoretical power required 
to move the air and they should be at least doubled to allow for 
the fan and engine friction and the power required to run the fan 
considering it was moving no air and to overcome the friction 
of the air in the fan casing. 




Plate 14 — Cross Sectiov, Mwh^tt^m Umiww Comp\n\ s Power Station, New \opk Cit\ 

GBORGE H. PEGRAM, CH. ENG'R; W. E. BAKER, MECH. ESG'r; L. B. STILLWELL, ELEC. ENG'R. 



STEAM POWER PLANTS. 129 

With induced draft the. air is of less density on account of its 
higher temperature, so that less power is required per cubic foot 
of gas moved. If the gases have a temperature of 600 degrees 
the quantities given in the last column of Table I can be multiplied 
by 0.5, and by 0.58 if the temperature is 450 degrees, to obtain the 
actual power required to move the air. . The engine driving the 
fan should have its cylinders so proportioned that it can easily 
develop power 50 per cent, in excess of that calculated. 

Table III shows the capacity of the American Blower Com- 
pany's fans used for induced draft, according to its catalogue. 

TABLE II.— REVOLUTIONS OF FAN OF GIVEN DIAMETER NECESSARY 
TO MAINTAIN A GIVEN PRESSURE OVER AN AREA WHICH IS WITHIN 
THE CAPACITY OF THE FAN. 

o'3 









Pressure, in 


Ounces 


per Square Inch. 






Va 


% 


% 


¥2 


% 


% 


% 


1 


IVs 


IV4 


3 

4 


194 
166 
146 
129 


274 
235 
206 
183 


336 

288 
252 
224 


388 
332 
291 
258 


433 
372 
325 

289 


475 
407 
356 
316 


513 
439 
384 
342 


548 
469 
411 
365 


581 
498 
436 
387 


612 
525 
459 
408 


5 


116 

106 

97 

90 


164 
149 
137 
126 


202 
183 
168 
155 


232 
211 
194 
179 


260 
236 
217 

200 


285 
259 
238 
219 


308 
280 
256 
236 


329 
299 
274 
253 


349 

317 
290 
268 


367 

'664: 

306 

282 


8% 


83 
78 
73 
69 


117 

110 

103 

97 


144 
135 
126 
119 


166 
155 
146 
137 


186 
173 
163 
153 


203 
190 
178 
167 


220 
204 
192 
181 


235 
219 
205 
194 


240 
232 
218 
205 


262 
245 

230 
216 


9 
11 


65 
61 
58 
53 


92 

87 
82 
75 


112 

106 

101 

92 


129 
123 
116 
106 


144 
137 
130 
118 


158 
149 
142 
129 


171 
162 
154 
140 


183 
173 
164 
150 


194 
183 
174 
158 


204 
193 
184 
167 


12 
13 
14 
15 


49 
45 
42 
39 


69 
63 
59 
55 


84 
78 
72 
67 


97 
90 
83 

78 


108 

100 

93 

87 


119 

110 

102 

95 


128 
116 
110 
102 


137 
126 
117 
110 


145 
130 
124 
116 


153 
141 
131 
122 



It is based on a temperature of 550 degrees Fahrenheit for the 
gases, and air temperature of 62 degrees, on 18 pounds or 234 
cubic feet of air per pound of coal, and a consumption of five 
pounds of coal per boiler horse-power. Mr. F. R. Still, of the 
American Blower Company, recently wrote as toilows explaining 
it: "This table gives the diameter of the fan wheel, width at 
periphery, diameter of the inlet, size of the outlet and the max- 
imum speed necessary to produce a draft of one inch of water, 
which is about the strongest draft that is ordinarily required. 
The table also gives the capacity of the fan per inch of width (of 



130 STEAM POWER PLANTS. 

blade) at periphery, and the horse-power per inch of width. If 
it is desired to run the fan at a slower speed than is given op- 
posite any of our sizes, determine on the speed at which the fan 
is to run, find the capacity of same per inch width and divide 

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the required capacity for a given horse-power in the plant by this 
capacity per inch and it will determine how wide the fan should 
be at the periphery, with the increased diameter and the slower 
speed. The horse-power can be determined by multiplying this 
width by the horse-power per inches in width." 



^^T^ 




I Vertical Section.. ' 
Chimney Lincoln Whaei? Station, Boston 
Elevated Railway Company. 

GEORGE A. KIMBALL, CH. ENG'R. 



Plate 15. 



Chimney for U. S. Goveknment, Manila, P~ 

-TRONG, CON. ENG'r; EDWARD BARROTH. ARCi 



Chapter X. — Chimneys. 

Sise of Chimneys. — There are two factors that affect the ca- 
pacity of a chimney, its cross-sectional area and its height. The 
intensity or force of draft is proportional to the square root of 
the height of the chimney, and, for a given height, the capacity 
is directly proportional to its cross-sectional area within certain 
limits. Earlier in this book attention has been called to the 
importance of having a strong draft in order that cheap, low- 
grade fuels may be burned successfully, and also, that there may 
be sufficient reserve capacity in the boilers at times of abnormal 
demands. In this latter respect ample draft is just as good as ad- 
ditional boiler-heating surface, and, as a general proposition, it 
costs less. Although an engineer once said that high chimneys 
"are monuments to the folly of their builders," yet this opinion 
should not deter one from building chimneys from 150 to 200 
feet in height, and for very large plants still higher. In certain 
localities where smoke or obnoxious gases are objectionable, tall 
chimneys are necessary. Chimneys of the heights mentioned are 
desirable where high rates of combustion are to be employed, and 
the height of the chimney is governed somewhat by the amount 
of coal that is to be burned per square foot of grate in a given 
time. As most chimney formulas contain factors representing 
the height and sectional area, it is convenient to first fix the height 
suitable for the kind of coal to be burned and then determine the 
area by established formulas. 

Height of Chimneys. — Mr. J. J. De Kinder, an engineer of con- 
siderable experience in steam plant operation, recommends the 
following heights for chimneys with the coals mentioned : 75 feet 
for free-burning bituminous coal, 100 feet for slow-burning bit- 
uminous slack, 115 feet for slow-burning bituminous coal, 125 
feet for anthracite pea coal, 150 feet for anthracite buckwheat 
coal. These recommendations are probably intended for boiler 
plants of moderate size only. The author believes that with west- 
ern coals such as Collinsville or Mt. Olive a 150- foot stack is 



132 STEAM POWER PLANTS. 

desirable. This will make it possible to burn as a maximum at 
times of overload from 30 to 35 pounds of coal per square foot 
of grate per hour, this coal being burned ordinarily at 20 pounds 
per square foot of grate per hour. With plants operating 800 
or more horse-power of boilers, 150 feet is the minimum height 
of a chimney that should be selected, irrespective of the kind of 
coal that is to be burned. For large plants 200 feet is not exces- 
sive. No designer knows when the cost of coal may be such that 
it will be cheaper to burn low-grade fuels, which cannot be done 
without strong draft. 

Capacity of Chimneys. — Most chimney formulas are based on 
coal consumption but do not take into account the fact that the 
amount of gases given off by different coals varies. Col. E. D. 
Meier has called attention to this, and by calculating the volume 
of gases from their composition finds that the relative areas for 
chimneys for certain much used coals should be as follows : An- 
thracite 100, New River (Va. semi-bit.) 93, Youghiogheny 
(Penn. bit.) 102, Mt. Olive (111. bit.) 128, Collinsville (111. bit.) 

138. 

Three well-known chimney formulas are those of Kent, Gale 
and Christie. In the former 

H,P. = 3.33E/H 
in which H is the height in feet and E is the effective area, the 
actual area being determined by increasing the diameter of the 
chimney if it be round or the side of the chimney if it be square 
by 4 inches to allow for the lining of the chimney by a layer of 
gas that is assumed to have no velocity. E is approximately equal 
to (A — 0.6 V A) for round chimneys and to A — V3 V A for 
square chimneys. As this formula is based upon the burning of 
5 pounds of coal per horse power 

C=i6.6 E /H 

where C equals the number of pounds of coal burned per hour. 
The Kent formula assumes that the height and area are interde- 
pendent, and it only holds within certain limits. 
Gale's formula may be expressed in the form 

A = o.o7C^^andH=£!e/C.\2 

in which t is the temperature of the chimney gases and G the grate 
area in square feet. Col. E. D. Meier, who has a great deal of ex- 



STEAM POWER PLANTS. 



^I.34€' 



|...^,|„...i^i33i 



£Ll?iL 




El. SOT- 



Section at Elev43'6' 

Section at Elev I5'0* 

Figure 52.— Chimney Metropolitan Street Railway Co., New York. 



134 STEAM POWER PLANTS. 

perience with western coals, states that this formula gives rather 
too large results and recommends that 

and that after the height is found by this formula the area be ob- 
tained by the one proposed by Mr. Kent. 

Mr. George A. Orrok in a recent issue of "Power" states that 
the constant in the general chimney formula, for which Kent 
gives the value of 16.66, varies greatly in the formulas of differ- 
ent authorities, and Mr. Orrok recommends that a value of 12 
be given it for brick-lined stacks, but that in case of an unlined 
steel stack the value of this constant may be increased to 14 or 15 
and for small stacks 16 may be used. 

Mr. W. W. Christie in his book on "Chimney Design" gives 
the chimney formula : Horse power = 3.24 A i/ H, it being as- 
sumed that four pounds of coal are burned per horse power, A 
being the area of the flue and H the height, both in feet. If C is 
the coal burned per hour C = 12.96 A 1/ H. 

Thickness of Chimney Walls. — In designing a chimney of a 
given height and inside diameter it is necessary to determine the 
thickness of the walls required to provide sufficient weight to 
prevent its being overthrown by the wind. It is customary to 
step out the inner walls at different levels so as to divide the shell 
into a series of sections, each of a uniform thickness which is less 
than that of the section immediately below it. As the walls have 
a slight batter inside and outside, the diameters at the top and 
bottom and the thickness and heights of the different sections of 
the shell have to be determined. To simplify the problem it is 
proposed to give a method of designing a chimney with straight 
inner and outer walls of the proper batter. From this a chimney 
of approximately equivalent weight but made up of several sec- 
tions each of uniform thickness can be designed. 

It is usually customary to make the weight of a chimney such 
that it will bear a certain relation to the wind pressure, a 
rule commonly used requiring that the prolongation of the 
resultant of the total wind pressure acting through the 
center pressure and the weight of the chimney intersect 
a horizontal plane through the chimney base at a point not 
more remote from the axis of the chimney than a dis- 
tance equal to D^, -^ 6 where D^ represents the outside 



Cast Iron Caps Bedded 
in Portland Cement. 



%lr^Band5''li' 
J 6'7'ffad. • 




Section E-F. 

T.t tMMUKn KgCQWa 



Figure 53.— Brick Chimney Designed by Lockwood, Greene & Co. 



136 STEAM POWER PLANTS. 

diameter at the base, or at the elevation at which the calculation 
for stability is made. If the chimney be round, square or octag- 
onal, the diameters referred to are those of the inscribed circles. 
To illustrate, if, in Figure 54, CD represents the wind pressure 
considered to be acting through the center of pressure C and CE 
represents the weight of the chimney, and the prolongation of 
their resultant CF intersects the base AB at a point G distant 
from H by a distance less than D^ -^ 6, then the conditions as 
to stability are fulfilled. In Figure 54, C is the center of pres- 
sure ; CD represents the total wind pressure, P ; CE the weight 
W, and CH equals h the height in feet of the center of pressure 
above the base AB. Expressed algebraically the formula is: 

W h 

The value of W can be found from the volume of the chimney, 
assuming that one cubic foot of brick masonry weighs 115 pounds. 
Then W=ii5 V. Therefore 

W = „5 H . ^ (D,/ + D/ + D,T,,)^ a If + d/ + d.d.) -^ (^^ 

Throughout this discussion the terms used have the following 
significance : 

H = height of chimney above base in feet. 

h = height of center of pressure above base in feet. 

D^ = outside diameter top in feet. 

d^ --= inside diameter top in feet. 

D^ = outside diameter bottom in feet. 

d^ = inside diameter bottom in feet. 

P = equivalent total wind pressure. 

Now if the value of W in equation (2) be substituted for W in 
equation ( i ) then : 

^ H AD^'+D/^ + D^D/) - (d/.'^ + d,^4-d/.dO \ ^ 6hP 
"V 12 J T>b 



115 



There is but one factor in this equation, d^, whose numerical 
value is not known either from data assumed at the outset or from 
its relation to known quantities in the equation. This being the 
case the equation can be solved for the value of d^ and its numer- 



STEAM POWER PLANTS. 



137 



ical value obtained. One would then have all the dimensions of 
a chimney with straight walls of a height and inside diameter 
necessary, and which would satisfy conditions of stability. 

The inside diameter of the chimney at the top and the height 
must be assumed. From the former dimension the outside diam- 



■If 



^ 



L 



m 



.k_k 



,B 



H 






\ 



J 



k- Z. 



r 




Figure 54. 



Figure 55. 



Figure 5G 



338 STEAM POWER PLANTS. 

eter at the top and the outside diameter at the bottom can be found 
readily by two empirical rules. The first of these is Prof. Lang's 
rule, given in his paper on the ''Construction and Dimensions of 
Chimneys for Boiler Plants," of which a translation was printed 
in The Engineering Record of July 20 and 2y, 1901. It is to the 
effect that the thickness in feet of a chimney at the top, t, neglect- 
ing the ornamentation, should be 

t = 0.328 -|- 0-05 d^+ 0.0005 H 
therefore 

D/ = d^ -}- 2t = 0.656 -|- I.I d/ -}- o.ooi H (4) 

The minimum value of t should be 0.58 feet for radial brick 
and 0.7 feet for common brick. As the thickness must be over 
a brick's length and as it cannot increase by less than half a brick's 
length, the value of t must be 0.7, 1.08 feet, etc. Few chimneys 
built of common brick have a value for t greater than 1.08 feet. 
The outside diameter at the bottom, or D^, can be obtained from 
the outside diameter at the top by a rule which assumes a batter 
for the outside wall of 1 130 to 1 136 on a side. Assuming it to 
be 1 132 then : 

substituting the value of D^- from (4) then 

TT 

D^ = 0.656 -f i-i d/ 4" o.ooi H -| — = 0.656 -f- I.I d/ -|- 0.063 H. 

The value for P, the total wind pressure in equation (3), is 
found by multiplying the assumed wind pressure of 50 pounds per 
square foot by the equivalent of the vertical cross-section of the 
chimney through the axis, in square feet. With a square chim- 
ney this plane is taken parallel to two opposite sides. For square 
chimneys P has a value equal to their cross section in square feet ; 
for round chimneys 0.50 times this area, and for octagonal ones 
0.71 times this area. 

The numerical values of H, D^, D^, d/, P and H found in the 
manner indicated are substituted in the above equation, which 
then can be solved for the value of d^. This determined we have 
all the dimensions of the straight walled chimney of the height 
and inside diameter required for the capacity, and which fulfills 
the conditions as to stability. As has been said, the interior of a 
chimney is seldom constructed with a straight batter, but in a 
series of steps each section from the top downward increasing 



^KTCm 



H 



STEAM POWER PLANTS. 



139 



in thickness by half a brick's length. Each 
step should then be of a thickness in inches 
that is divisible by 4j^, this being the width 
of a brick and the necessary mortar. From 
the top down, therefore, the thicknesses of the 
different sections should be 8^^, 13, 173^, 22, 
26,^ etc., inches. Should the calculations for 
the thickness of the wall at the bottom call for 
a thickness intermediate between two of these 
thicknesses, the greater 
one can be selected, as 
the thickness of the bot- 
tom section. Should 
such calculation show 
that the thickness at the 
bottom should be 22 
inches, the chimney can 
be divided into four sec- 
tions of equal height, 
8^, 13, 173^ and 22 
inches thick. Radial 
brick for chimneys are 
made in several sizes so 
that the thickness, when 
they are used, increases 
by about 2 inches at the 
offsets. 

After the thickness of 
walls of the different 
sections and their 
heights are determined, 
the calculation for sta- 
bility must be made at 
the base of each section, 
paying no attention to 
that below. For in- 
stance in Figure 55, the 

^ ,. ^ p. stability of the part 
Section C-D. , ^^^ , ,, , . 

THE ENG,NEER.NQ REcoi- ABJI shouM bc calcU" 

FiGURE 57.— CusTODis Radial Brick Chimney lated considering IJ a» 

FOR Orford Copper Co. 




140 STEAM POWER PLANTS. 

the base, also ABHG considering GH the base, etc., each time 
locating the center of pressure for the part under consideration. 

Another operation yet remains, and that is to find the pressure 
imposed upon the brickwork by its own weight. Calculation must 
be made as to the pressure per square inch at the base, and at 
each level where the shell changes in thickness, that is, at the bot- 
tom of each section. According to Prof. Lang, the pressure in 
pounds per square inch should nowhere exceed that given by the 
formula P == 71 + 0.65 L where L denotes the distance in feet 
from the top of the chimney to the point in question. Should the 
pressure exceed that given by the formula the walls of the chim- 
ney should be made thicker. The function of the chimney height 
is introduced in the formula to allow a greater pressure in high 
chimneys, which are erected less quickly than shorter ones, the 
mortar therefore having more time to harden. 

Chimney Linings, Etc. — Chimneys of common brick built in the 
United States are usually provided with an inner core or lining 
to protect the outer shell from the heat. Sometimes this core is 
carried up for half the height of the chimney, but more usually 
to the top. Care should be taken that it is built independently 
of the outer shell as the greater expansion of the core would in- 
jure the shell. With radial brick chimneys the inner core is not so 
common as the bricks are more carefully burned and selected than 
is the custom with common brick and are not so easily affected 
by heat. Any chimney likely to contain gases at a higher tem- 
perature than 600 degrees Fahrenheit should be lined with fire- 
brick set in fire clay or lime mortar, preferably the former. Some- 
times the fire-brick lining extends from the bottom to one-third 
or one-half of the height. The core can be divided into sections, 
each about 40 to 50 feet high, and 4, 8^, 13, 173^ and 21 inches 
in thickness from the top down. If the chimney is of fairly large 
diameter the 4-inch section should not be over 25 or 30 feet. In 
the largest chimneys 8 inches is the minimum thickness of the 
core. It usually has a uniform inside diameter so that changes in 
thickness are secured by offsets on the outside. With the batter 
for the outer surface of the outside shell recommended in an ear- 
lier paragraph there is likely to be sufficient distance between the 
offsets of the core and those of the outer shell to provide proper 
clearance. When the chimney is drawn on paper this can be de- 
termined. Steel chimneys should also be lined to prevent loss of 



STEAM POWER PLANTS. 



141 




Boiltrs 



Figure 58. — Chimney, Laidlaw-Dunn-Gordon Co., Cincinnati^ O. 



142 STEAM POWER PLANTS. 

heat and also air leakage, which will occur unless the joints are 
carefully calked, a provision that is frequently overlooked. 

In constructing the opening for smoke flues at the base of the 
chimney care should be taken that it is not weakened at that point. 
The top of the opening should be arched over or spanned with 
heavy steel beams built in the masonry. Should the chimney have 
an inner core the smoke flue should, of course, be continuous 
through both shells. Ladders for reaching the top of a chimney 
are usually located on the inside of brick chimneys and more fre- 
quently on the outside of steel ones. If the latter, the continuous 
hand rails at the sides should be so designed as to allow for the 
possibility of a difference in expansion between the ladder and 
the chimney. The tops of brick chimneys should be covered with 
a cast-iron cap held in place by anchor bolts, and lightning rods 
metallically connected to the ground should also be provided. 

Materials. — Masonry chimneys are usually built of brick, but 
recently concrete chimneys reinforced with steel, as in the Ran- 
some chimney, shown in Figure 59, have been used with success. 
For brick chimneys hard burned brick of high specific gravity 
should be used. A special brick for chimney building used to a 
large extent in Europe and in a rapidly increasing extent in the 
United States is the radial brick for round chimneys, with its 
inner and outer surface curved to conform to the curvature of 
the chimney. Several holes running through the brick aid in the 
burning and also serve to secure it in place more strongly as the 
mortar works into them when the brick is laid. The radial brick 
that have been used to a considerable extent by the Custodis and 
Heinicke companies in Germany are much stronger and more dur- 
able than common brick. Another feature in their favor is that 
they are considerably larger than common brick and less labor 
is required in laying them. 

Masonry Chimney Foundations. — These should be of such an 
area that the load per square foot does not exceed one ton per 
square foot on soft clay; two tons per square foot on stiff clay, 
compact sand, loam, etc. These loads are exceeded in buildings 
but they should not be in chimneys unless solid rock underlies the 
foundation. The rock should be dressed off into steps with ver- 
tical sides so there will be no tendency to slide. With very large 
masonry chimneys and in fact with chimneys of moderate size in 
soil of low bearing power, pile foundations are frequently re- 



STEAM. POWER PLANTS. 



143 



k'jwishd Stzet 




BarsZ'0'Long.l8''O.C. 



Vertical Bars k"Twlsiz(f 
Stzzl. 

[/'Zr-fical Bars ^' 
Twisied Steel. 



Rings of ^"Tiv'isfzcl 

5tzzl Bars. Z'd'O.C. 

Rings ofl^^Twjsfed 

Sfzel Bars l'3^0.C 



Half Section,, 



' Twisted Steel Bars. 
Half Elevation. 



Half Plan of Footing 
showing Piling. 



Figure 59. — Ransome Concrete- Steel Chimney^ Central Lard 



4' 

Steel Bars. 
Half Plan of Footing 
showing Steel. 

TIN iwimfiw «COO*l> 

Co., Hoboken, N. J. 



144 STEAM POWER PLANTS. 

sorted to, the piles being driven on about 23^ foot centers and cut 
off below the level of surface water ; they support a concrete bed 
two or more feet in thickness into which their tops extend. Con- 
crete or brick foundations laid in cement mortar should be laid 
several weeks before the chimney is constructed in order that the 
cement should set properly. The sides of the foundations which 
are usually in the form of a truncated pyramid should have an 
inclination of at least 60 degrees to the horizontal. The depth of 
the foundation should be such as to properly distribute the load. 

Steel Chimneys. — Chimneys built of sheet steel are common, 
particularly in Pennsylvania and the middle West. They may 
be either self-supporting or held in position by means of guy 
ropes. To save expense, it is not unusual for a considerable 
number of small guyed chimneys to be used in place of one large 
chimney. Steel chimneys are said to cost less than those built 
of brick but the market price of steel affects their relative cost 
considerably. Any steel chimney should be carefully calked at 
the joints and the vertical lap joints scarfed at the girth seams. 
The leakage of air that would otherwise occur and which unfor- 
tunately does occur in many cheaply built steel chimneys very 
greatly affects the draft. Self-supporting steel chimneys rest 
usually on cast iron base plates sometimes cast in sections and 
bolted together if the chimney be large enough to make this de- 
sirable. The base plate is held down by foundation bolts built in 
a brick or concrete foundation sufficiently heavy to prevent the 
chimney from overturning. The lower courses of a self-support- 
ing stack are usually flared out at the base of the chimney in a 
conical or bell shape, to give stiffness to it, the height of this cone 
or bell being from i^ to 2 times the diameter of the chimney 
above the bell and of a diameter at the base equal to the height of 
the bell. 

A formula for determining the thickness of shell that is used 

by a firm which has built a large number of large self-supporting 

steel chimneys is as follows : 

Moment in inch pounds ,. , . , 

5 T^i = stress oer Imeal mch. 

0.78450^ 

This assumes that the moment of the total wind pressure in 
pounds multiplied into the distance in inches of the section under 
consideration from the center of pressure, divided by the diam- 
eter of the chimney in inches squared multiplied by 0.7854, is 



STEAM POWER PLANTS. 



145 



fZll^- 



zm 



.23Sk: 



, 7/3'fiivels 



f--n'6-^ 




r' 


Brxket . 


i 

i 


o| k^ B 


■<»■ 


^, 'P. B 


1 


oi id / 


i 

i... 


°i pi / 

0. •dj 






^^^^ 


f --m- 


•A /It-^ ,<^y7*i^,;« 




.''^'"^'^ O y -^ 


r-v V 


^-^-.lL.9.iL.9... 


vrf' 




i 


«. /5'. 


*-^^ti 





^-//{?'Z^ 




Tdi cweiaMuna *T"°<^ < 



ELEWTION OF SEGMENT ON LINE X-X . 

Figure 60. — Steel Chimney at Wilmerding, Pa, 

BUILT BY THE RITER-CONLEY MANUFACTURING CO. 



146 STEAM POWER PLANTS. 

equal to the maximum stress per lineal inch in the shell. The 
total wind pressure is based on an assumed pressure of 25 pounds 
per square foot of projected area. A safe working stress is 10,000 
pounds per square inch and this should be reduced by the efficiency 
of the riveted joint. If the efficiency of the riveted joint is 60 per 
cent., then 6,000 pounds per lineal inch would be a safe working 
strength and the ratio of the stress per lineal inch, as found by 
the equation, to 6,000 would be the thickness in inches of the 
shell required at the section under consideration. Calculation for 
the thickness of the shell should be made at the base of the stack, 
the top of the bell and several points between it and the top. The 
greatest strain occurs at the top of the bell. On account of de- 
terioration that is apt to occur in the steel, it is undesirable to use 
shells less than ^ to }i inch in thickness, depending upon the 
size of the chimney. This is particularly true near the top where 
the greatest corrosion is apt to occur, owing to the effect of the 
smoke that usually clings to the lee-side of a chimney. 

For about one-fifth or one-quarter the height of a sqlf-support- 
ing chimney it is desirable that the girth seams be double-riveted. 
The lower edge of any sheet usually overlaps the upper edge of 
the sheet beneath it. For the sake of the greater stiffness, the 
vertical seams at the bell should also be double-riveted. 

Foundations for Self -Sup porting Steel Chimneys. — The foun- 
dations for self-supporting steel chimneys should have such a base 
that the load caused by the weight of the chimney and base and 
by the wind pressure on the leeward half of the base does not ex- 
ceed the requirements of safety. The weight of the lining, if there 
be any, is to be neglected. The foundation must have sufficient 
mass so that the moment of the wind pressure into the height of 
the foundation plus half the height of the steel shell shall be equal 
to the weight of the shell plus the weight of the foundation into 
one-third the length of the base of the foundation. 

If P is the total wind pressure, Ws the weight of the stack, Wf 
the weight of the foundation, all in pounds, then in Figure 56 the 
conditions as to stability are fulfilled when 

p(!L+h)=(w, + w,)| 

The wind pressure can be obtained by calculation and the 
height of the foundation can be taken at from one-eighth to one- 
tenth the total height of the chimney. With these data and the 



STEAM POWER PLANTS. 147 

weight of the stack being known, the weight of the foundation 
can be calculated. As concrete weighs about 140 pounds per cubic 
foot, the volume of the foundation can be determined and from 
this the area of the top and bottom. The slope of the sides can 
be to I to 3. Should the wind pressure be found to cause too great 
a load along the leeward edge of the foundations, a foundation of 
less depth which would insure one of greater area, can be assumed. 



Chapter XL — Coal Handling, Water Supply and Purifi- 
cation. 

Coal Handling Machinery. — One of the most important factors 
governing the selection of a location for a steam power plant is 
the cost at which coal, assuming that fuel is to be used, can be 
transported to the boiler plant and the cost of the disposal of the 
ashes. Because coal can frequently be conveyed more cheaply by 
water than by rail large power plants are located upon navigable 
waterways, if it is convenient to do so, and if not, the site should 
be near a railroad if possible, so that coal can be delivered at the 
minimum expense. Of course the expenditure to which one 
should go in providing means for handling coal and ashes de- 
pends entirely upon the amount to be burned, as the cost of han- 
dling coal may be so small compared to other expenses as to be of 
secondary consideration. Even in the smallest plants, however, 
thought should be given the matter of coal delivery. If coal- 
handling machinery is not used it is a convenient arrangement 
to have coal pockets or coal bunkers located next to the wall of 
a boiler room so that coal will fall from them by gravity to the 
floor in front of the furnace doors. If possible, arrangements 
should be made for delivering the coal to the bunkers directly 
from the coal cars, whether they be steam railroad coal cars or 
small dumping cars of an automatic railway run from some 
nearby wharf. As plants increase in size greater expense for 
coal handling apparatus is warranted. Means should be pro- 
vided for storing coal and the amount of storage space required 
depends, in a measure, upon the effect of an enforced shut down. 
For an electric lighting or railway power station, or for power 
and heat for hospital buildings or public institutions, large stor- 
age capacity is imperative, particularly in localities where there 
is likely to be an interruption in the supply of fuel. 

With plants as small as 500 or 600 horse power in boilers, coal- 
handling machinery is frequently installed. It usually consists 
of a receiving hopper, into which the coal is delivered, feeding 



STEAM POWER PLANTS. 



149 



to an endless chain of buckets which elevates and conveys the 
coal to bunkers placed over the boilers; spouts lead from the 
bunkers to the floor near the furnace doors of the boilers if they 
are hand fired or to mechanical stokers if the latter are provided. 
Frequently the conveyor is arranged to pass beneath ash hoppers 
under the boiler grates so that when not handling coal it can be 
used to elevate the ashes into a storage bin, from which they can 
be removed by carts or otherwise. When coal is delivered by 
boat to a plant, particularly in large stations, it is frequently ele- 
vated by a self-filling bucket and raised by a boom to an elevated 
coal hopper in a tower on the wharf; the coal falls through a 




^-iSii^ 9'7£'-^^-^ 97/^^4;-^'8|4 



Figure 61. — Cross-Section Power House Central Lard Co. 



crusher to reduce it in size and then passes through automatic 
weighing scales to the conveyors which deliver it into bunkers 
over the" boilers. Sometimes large storage bunkers are built out- 
side of a power house, these being filled by conveyors, while a 
second conveyor extends from the storage bunker to a smaller 
bunker over the boilers. Some idea of the varied manner in 
which coal handling machinery for power houses may be applied 
can be had by examining the illustrated catalogues of makers of 
this class of machinery. 

Cost of Coal Handling by Machinery. — For the purpose of 
showing the relative cost of hand firing and a modern coal-han- 



150 STEAM POWER PLANTS. 

dling equipment combined with mechanical stokers in large plants, 
some pertinent figures have been obtained through the courtesy 
of a well-known electrical supply company owning a plant, con- 
taining about 7,500 horse-power in boilers, which was operated 
for some time after construction without any kind of coal-han- 
dling machinery other than small hand cars which were loaded 
by hand from railway cars outside of the building and then 
hauled up a slight incline to the boiler house, so that the fuel 
could be dumped in front of the furnaces. The cost is given for 
two months, a year apart ; during the first month, the plant was 
run without and during the second month with coal-handling ma- 
chinery and mechanical stokers. The coal-handling plant con- 
sisted of a McCaslin conveyor so arranged that the coal was only 
handled by hand in shoveling it out of railway cars onto the con- 
veying system : 

Tons 

of coal Cost 

May, 1900. Wages, burned, per ton. 

16 firemen and one helper. $981.80 4,292 $0,229 

11 coal and ash men. Ash removing by contract. .. 634.66 0.1478 

May, 1901. 

3 firemen and 2 helpers 287.75 6,975 0.041 

11 coal and ash men, 2 conveyor men 654.50 0.0938 

The saving in wages of firemen and helpers amounts to 18.8 
cents per ton, which is 82.1 per cent, or $1,311.30 per month. The 
saving on coal and ash handling is 5.4 cents per ton, which is 
41.4 per cent, or $376.55 per month, or a total saving of $1,687.85 
per month or over $20,000 per year. Were it not for the fact 
that, owing to peculiar local conditions the coal has to be shoveled 
from the coal cars onto the conveyor system the cost of labor 
might be still further reduced. 

Cost of Boiler-Room Labor, — This matter is of importance in 
deciding upon methods of handling coal in steam power plants 
and some valuable information in this connection was contained 
in a report by Mr. R. S. Hale to the Steam Users' Association, 
whose members represented nearly 400 mill owners, largely in 
New England and the Middle States. Judging from the replies 
received from members owning a total of about 600 boilers, it 
costs to move coal by hand (wheel barrow) about 1.6 cents per 
ton per yard up to distances of five yards, then about o.i cent per 
ton per yard for each additional yard. Mr. Hale found that one 
man, besides a night man, can run an engine and fire up to about 



STEAM POWER PLANTS. 



151 



1^ ^ ^^^ 







152 STEAM POWER PLANTS. 

10 tons of coal per week. One man, besides an engineer and 
night man, can fire up to about 35 tons per week. Two men, be- 
sides an engineer and night man, can fire up to about 80 tons per 
week. These figures assume that the night man does all he can 
of the banking, cleaning and starting. The figures are for aver- 
age conditions. If the conditions are exceptional, as, for in- 
stance, where there is a very long wheeling distance or a very 
variable load, proper allowance should be made. Mr. Hale states 
in the report that mechanical stokers save from 30 to 40 per cent, 
of the labor in plants burning from 50 to 150 tons per week and 
save no labor in small plants. Boiler attendants are paid about 
$1.50 per day, working from 10 to 12 hours. The average cost 
of firing coal, according to the report, was 48 cents per ton, the 
maximum 71 cents and the minimum 26 cents. 

Mechanical Stokers. — In the chapter on mechanical draft it 
was explained that perfect combustion required just the proper 
amount of air to be supplied the furnace of a steam boiler. That 
requirement is difficult to fulfill where fuel is fired by hand. If 
the bed of fuel is too thin there will be an excess of air, and if 
too thick too little air will enter the furnace, both of which will 
cause a loss for reasons previously explained. This is particu- 
larly true with bituminous coals. Theoretically, therefore, the 
best result would be obtained by firing small quantities at frequent 
intervals rather than larger quantities of fuel less often. Fre- 
quent firing requires that the fire doors be opened often, and this 
means a loss due to too much air entering while the doors are 
open. The practical objection to frequent firing lies in the fact 
that it is difficult to get a fireman who will fire a boiler properly, 
most of men who perform this kind of labor being of the class 
that prefers shoveling a large amount of fuel into the furnace 
and then sitting down for half an hour than to shoveling a lesser 
amount at shorter intervals. The kind of men who take an in- 
terest in stoking properly, and do it, are not likely to remain fire- 
men. For the reasons given, the only way in which coal can be 
supplied to a furnace in such a manner as to produce the best 
results is by mechanical means or mechanical stokers. There is 
every reason to believe that a plant of boilers using bituminous 
coal mechanically fired will operate with a sufficient economy of 
fuel over hand-fired boilers to pay a good return on the increased 
investment required for the stoking apparatus. This result can 



I 



STEiM POWER PLANTS, 



153 



1^ 




l>r-i fe 



O 

o 

H 
C/3 



154 STEAM POWER PLANTS. 

be effected by an5^ fireman who is sufficiently intelligent to do 
ordinary firing but not, however, unless the mechanical stoker is 
given some attention to see that holes in the fire do not occur or 
that clinker does not form to impede the uniform movement of 
the coal. The stoker is not wholly automatic, but, given a fair 
degree of attention, it is an indispensable aid to the firemen in the 
attainment of the perfect combustion of bituminous coal. Me- 
chanical stokers are also of value in reducing smoke with bitum- 
inous coal and reducing the number of men in the boiler plants. 
They are of particular value in making it possible to burn low- 
grade smoking coals in situations where the emission of smoke 
would be objectionable. As an improper air supply affects the 
amount of smoke emitted by coal, mechanical stokers properly 
designed very much reduce the smoke and oftentimes entirely do 
away with it. 

Burning Pulverized Fuel. — There is one method of mechan- 
ically supplying coal to boilers that gives promise of much suc- 
cess and that is after pulverization. The principal difficulty that 
has been met in the past has been the expense of pulverizing, but 
recently methods have come into use that make this method com- 
mercially possible. Various types of mills for this purpose have 
been in use in the cement industry, ever since the development 
of the rotary kiln, that have given excellent satisfaction. Bitum- 
inous coal is ground and stored in hoppers from which it is de- 
Hvered usually by a small screw conveyor to a pipe about four 
inches in diameter and terminating in the mouth of the kiln in 
which the cement is burned. A blast of air passing through the 
pipe delivers the coal to the kiln where it burns. The jet of flame 
is six or eight feet long and of such an intensity that it could not 
be introduced directly under a steam boiler, hence a boiler would 
have to be equipped with a detached or separate furnace to use 
fuel in this way. One difficulty with this method of using pulver- 
ized fuel lies in the danger of storing it in quantities and to over- 
come this machines have been devised to pulverize the coal and 
deliver it directly to the furnace, each boiler being equipped with 
a pulverizer. By pulverizing the fuel the combustion of all the 
coal is complete as there is no loss due to the falling of fine par- 
ticles of coal through the grate bars as there is in other methods 
of firing. The relative amounts of air and coal supplied can be 
adjusted to a nicety hence there is no loss through too little or 




TravzHnq v 




STEAM POWER PLANTS. 



155 



too much air. Furthermore, the coal can be burned with abso- 
lutely no smoke. 

Supply of Boiler Water. — The amount of water used for steam 
boilers in large plants is of such a quantity that an abundant sup- 
ply of good water at low cost is a deciding factor in the selection 
of a site for a power house. The cost of water from city mains 
is usually such that it is desirable for large plants to go to some 
other source, as a river if one be available, artesian wells, etc. 
Before determining upon a supply, investigation should be made 




Figure 64. — Coal Bunkers Designed by Sheaff & Jaasted. 



as to whether or not the water is suitable for boiler purposes, the 
opinion of a chemist, not a boiler-compound quack, being obtained 
upon this point. Water may be unfit for boiler purposes without 
treatment on account of the presence of sewage which will cause 
foaming, or of certain salts which will form hard scale on the 
heating surface of the boilers and not only impair their efficiency 
but also entail large expense for cleaning them and be a source 
of probable danger besides. Deep well waters frequently contain 



156 STEAM POWER PLANTS. 

scale-forming salts and occasionally rivers receiving the rainfall 
from certain watersheds. River water is frequently contaminated 
with sewage. Sewage can probably be best removed for boiler 
purposes by mechanical filtration ; silt and mud by sedimentation 
and the same process. 

Water Softening. — The salts which give the most trouble in 
steam boiler waters by the formation of scale are the carbonates 
and sulphates of lime and magnesia. The presence in water of 
these salts, except the sulphate of magnesia, cause it to be hard, 
and their removal is known as water softening. Sulphate of mag- 
nesia does not cause scale to form, but it is precipitated by con- 
centration. Its presence prevents the removal of other salts by 
chemical treatment due to the fact that when lime water is added 
to water containing it, it breaks up and sulphate of lime results, 
which does form scale. A small quantity of carbonate of lime is 
apt to remain in solution in almost pure water, but if the water 
be saturated with carbonic acid the amount of carbonate of lime 
in solution can be very much greater; most of it being precip- 
itated when the carbonic acid is driven off, as it is when the water 
is heated. By adding lime water to water containing carbonate 
of lime and carbonic acid, the lime combines with the carbonic 
acid to form carbonate of lime which, while the carbonate of lime 
previously in the water, is precipitated because of the disappear- 
ance of the carbonic acid. Carbonate of magnesia is very similar 
in its properties to carbonate of lime. It is also acted upon by the 
lime water so as to form hydrate of magnesia, an almost insoluble 
salt, and carbonate of lime which is precipitated. The removal 
of the carbonates by the addition of lime water was proposed by 
an English chemist named Clark and this process generally bears 
his name. 

Sulphate of lime and sulphate of magnesia may be broken up 
by adding sodium carbonate, the former resulting in the forma- 
tion of calcium carbonate, which is precipitated, and sodium sul- 
phate, a non scale forming salt. The magnesium sulphate is split 
up into sodium sulphate and carbonate of magnesia and the latter 
can be further broken up by adding lime to cause an additional 
reaction in the manner described. The amount of sulphate of 
lime that can be dissolved in water depends upon the tempera- 
ture, but above a temperature of about loo degrees Fahrenheit 
the solubility of this salt diminishes. At .-^oo degrees Fahrenheit 



ii 



STEAM POWER PLANTS. 



157 



it is said to be insoluble. By heating with live steam, therefore, 
it is possible to precipitate nearly all of the sulphate of lime in 
water containing it. Quite a little time, however, is required to 
complete the reaction. Heating water carrying sulphate of lime 
previous to its entering a boiler will only remove the excess of 
sulphate of lime over that possible to retain in solution at the 
temperature to which the water is heated, so that unless it is 
heated to a high temperature chemical treatment is necessary to 
precipitate that not precipitated by heating. 

It will be noticed from what has been said that the carbonates 




■■'"({"(^""■'^^ 



Figure 65. — Typical Coal Elevating Tower. 



of lime and magnesia can be mostly removed by heating particu- 
larly if sufficient boiling occurs to drive off the carbonic acid, and 
some of the sulphate of lime can also be precipitated by heating. 
All of the four salts mentioned can be practically removed by 
chemical treatment. The heating method is more limited in its 
application but it is cheaper when it can be used. In certain cases 
chemical treatment or a combination of chemical treatment with 
the application of heat is alone possible. The best method can 
only be determined by a competent chemist after a proper inves- 



158 STEAM POWER PLANTS. 

tigation of the water is made, as it depends entirely upon the kind 
and quantity of sahs present in the water. 

Purifying with Exhaust Steam. — Almost all of the carbonates 
of lime and magnesia can be precipitated by moderate warming 
such as could be accomplished by exhaust steam in a feed-water 
heater of the open type. These are usually provided with trays 
over which the water trickles and filtering material to intercept 
the precipitated salts that do not lodge on the trays. Care should 
be taken that the heater is large enough to insure a low velocity 
of water passing through it to give time for the precipitation to 
occur in the heater and not in the boiler. Very often boiler waters 
are only objectionable because of the presence of salts which 
could be entirely removed practically in an exhaust-steam heater. 

Purifying by Live Steam. — A live-steam purifier is a device 
similar in a general way to most open-type feed-water heaters in 
that it consists of a shell containing a number of trays that can 
be withdrawn by removing the head of the heater, the trays being 
arranged one over the other so that the water trickles slowly 
downward over them so as to become thoroughly heated by the 
live steam under full boiler pressure that is admitted to the heater. 
The heater is usually located over the boilers so that water will 
run from it to the boilers by gravity. As live steam is used in 
these heaters and the temperature is higher, much more of the 
sulphate of lime present in water will be precipitated than there 
will in an exhaust steam heater. This type of heater will elimin- 
ate the carbonates of lime and magnesia. 

Purifying by Chemical Treatment. — The chemical treatment 
might be divided into two methods, the intermittent and contin- 
uous systems, and perhaps a third, with either combined with the 
application of heat to the water while being treated for the pur- 
pose of hastening the action of the reagents. The original Clark 
process was the intermittent method and it has been modified 
more or less by others. Usually this system consists of two large 
settling tanks in which the water to be treated is run, the proper 
amount of chemicals added, the mixture agitated and then 
allowed to stand for some hours while the precipitate settles, the 
clear treated water on top being used and the sludge that settles 
being blown off when necessary. This system usually requires 
two tanks so that the treatment can go on in one while purified 
water is being drawn from the other. An objection to it is the 



STEAM POWER PLANTS. 169 

first cost. With the continuous method the untreated or raw 
water and the necessary chemicals are mixed in the desired pro- 
portions, the supply of both being relatively constant, both being 
fed into a tank of generous size so arranged that the current is 
sufficiently slow for the precipitate to settle in the bottom of the 
tank, the clear water passing on to the outlet. The continuous 
treatment combined with heat has been used with no little success. 
The Sorge-Cochrane system of water purification consists in 
heating water almost to the boiling point, purifying by a simple 
chemical treatment and at the same time neutralizing 'such acids 
as are present in the water. The supply of water to the boilers 
is made up of all the pure condensation that can be saved and 
utilized, and of just enough fresh cold water supplementing this 
condensation to supply the demand. The conversion of the sul- 
phates and carbonates of lime and other soluble salts into insol- 
uble and neutral salts is accomplished in a specially designed feed 
water heater of the open type by introducing into the water to 
be tested, before it enters the heater, a suitable chemical such as 
soda ash and simultaneously heating the water. Means are pro- 
vided for varying the amount of the reagent, and also by means 
of a filter bed in the heater, of intercepting the precipitated salts 
and other insoluble matter. 



INDEX. 



Air needed for combustion 127 

Blowers, capacity of 126 

Blowers, design of 125 

Blowers, steam jet 122 

Blowers, theory of 124 

Boiler heating surface 12 

Boiler heating surface — division of in 

units 15 

Boiler horse power 13 

Boiler settings 30 

Boiler specifications 31, 36 

Boilers, design of tubular 22 

Boilers, grate surface in 16 

Boilers, riveting in 28 

Boilers, spacing of tubes in 26 

Boilers, thickness of shell..... 22 

Boilers, types of 13 

Boilers, specifications for water tube.. 39 

Chimney foundations 142, 146 

Chimney linings 140 

Chimneys 131 

Chimneys, capacity of 132 

Chimneys, height of 131 

Chimneys, materials for 142 

Chimneys, size of 131 

Chimneys, steel 144 

Chimneys, thickness of walls 134 

Combustion, theory of 121 

Coal, anthracite 21 

Coal, burning pulverized 154 

Coal, cost of handling 149 

Coal, different kinds of 19 

Coal, handling 3 

Coal handling machinery 148 

Coals, bituminous 20 

Coals, semi-bituminous 20 

Coals, value of steam 18 

Concrete 11 

Condensers 98 

Condensers, advantages of 98 

Condensers, guarantees for 110 

Condensers, jet 101 

Condensers, location of 104 

Condensers, proportioning 108 

Condensers, saving due to 99 

Condensers, siphon 103 

Condensers, sources of water supply 

for 10/ 

Condensers, specifications for 109 

Condensers, surface 102 

Condensers, types of 100 

Condensers, water necessary for.... 106 

Cooling towers for condensers 108 

Draft, mechanical 120, 122 

Draft, necessity of ample 121 

Drawings 4 

Drips, care of 79 



Economizers, use of 115 

Economizers, value of 117, 119 

Electric power, advantages of 3 

Engine auxiliaries 64 

Engine foundations 10 

Engines, economy of with variable 

load 54 

Engines, frames for 63 

Engines, guarantees for 66, 67 

Engines, horse power of — 

Engines, mean effective pressures 

for 48, 53 

Engines, methods of buying 42 

Engines, overload capacities 54 

Engines, piping for 66 

Engines, piston speed of 46 

Engines, proportioning cylinders for. 

49, 52 

Engines, reheaters for ..59, 63 

Engines, rotative speed of 46 

Engines, selection of types of 43 

Engine shafts 65 

Engines, specifications for 61 

Engines, steam consumption of 43 

Engines, steam jackets for 59, 63 

Engines, steam pressures for 45 

Engines, valve gear of 63 

Fans, capacity of 126 

Fans, design of 125 

Fans, theory of 124 

Feed water heatier, connection to.... 79 

Feed water heater guarantees 115 

Feed water heaters, condensation in.. 113 

Feed water heaters, proportioning . . . 112 

Feed water heaters, purchasing 114 

Feed water heaters, specifications for. 114 

Feed water heaters, types of Ill 

Feed water heaters, uses for 112 

Feed water heaters, value of Ill 

Foundations for buildings 6 

Foundations for engines 10 

Fuel, burning pulverized 154 

Grates in boilers, proportioning 17 

Grease separators 79 

Horse power, boiler 13 

Horse power, engine 44 

Oil separators 79 

Pipe coverings 95 

Pipe fittings, kinds of 92 

Pipe flanges, dimensions of 93 

Pipes, arrangement of steam 72 

Pipes, exhaust for condensing plants. 76 

Pipes, exhaust, size of 92 

Pipes, kinds of 86 

Pipes, pitch of steam 71 

Pipes, size of steam 88 

Shafts, engine 65 



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Note. — The Fourth Edition, greatly enlarged and almost 
entirely rewritten, about 750 pages, and 500 new illustrations, 
will be ready in October or November, 1904. The price is not 
yet fixed. 

Moisselff, L. S.— (See Considere.) 

Monroe, William S.— Steam Heating and Ventilation 

150 pages, 90 illustrations 2 00 

More, James, and Alex. M. McCallum— English Methods 
of Street Railway Track Construction 

Reprinted from the Street Railway Journal, Pamphlet. 26 
pages, illustrated 35 

Ohiy, J.— Analysis, Detection and Commercial Value of 
Rare Metals 

A treatise on the occurrence and distribution of the Rare Metals 
and Earths, the method of determination and their commer- 
cial value in the arts and industries, with a historical and statis- 
tical review of each. 216 pages. First edition^ with a supple- 
nientary chapter 3 CO 

Parham, E. C, and J. S. Shedd— Shop and Road Testing 
of Dynamos and Motors 

626 pages, 211 illustrations 2 50 

Poincare, H.— Maxwell's Theory and Wireless Telegraphy 

Part I. — Maxwell's Theory and Hertzian Oscillations, by H. 
Poincare, translated by Fred'k K. Vreeland. Part II. — The 
Principles of Wireless Telegraphy, by Fred'k K. Vreeland. 
Cloth, 260 pages, 145 illustrations 2 00 

Poole, C. P.— Wireman's Pocket Book 

In press ; ready shortly i 00 

Portraits of Founders of Electrical Science 

From Gilbert to Henry. Includes portraits of Gilbert, Guericke, 
Franklin, Galvani, Volta, Davy, Ampere, Faraday, Henry and 
Becquerel 25 



McGRAW PUBLISHING COMPANY. 



Pratt, Mason D., and C. A. Alden— Street Railway Roadbed 

A treatise on the construction of the roadbed, giving data as 
to rails, method of track fastening and making joints, guard 
rails, curves, etc. 135 pages, 157 illustrations $2 00 

Reed, Lyman C— American Meter Practice 

Cloth, 250 pages, illustrated 2 00 

Robinson, F. J.— Keys for the Practical Electrical Worker 

The Electric Light, Power, Street Railway, Telephone and the 
Telegraph explained and illustrated by drawings and diagrams 
of connections from the latest practice. 196 pages, flexible 
leather cover 2 00 

Saunders, W. L.— Compressed Air 

A cyclopedia containing practical papers on the production, 
transmission and use of compressed air. 1188 pages, 498 illus. 5 00 

Shepardson, George D.— Electrical Catechism 

450 pages, 325 illustrations 2 00 

Skinner, Frank W.— Types and Details of Bridge Con- 
struction 

Vol. I. — Arch Bridges: comprising (i) Wood and Iron Arch 
Spans; (ii) Spandrel Traced Arched Spans; (iii) Arch Truss 
Spans, and (iv) Plate Girder Arch Spans. Cloth, 306 pages, 
numerous illustrations 3 00 

Smith, Chas. F.— The Practical Testing of Dynamos and 
Motors 

231 pages, 83 illustrations 2 00 

Steinmetz, Charles Proteus — Theoretical Elements of 
Electrical Engineering 

Second edition. 320 pages, 148 illustrations 2 50 

The Theory and Calculation of Alternating Cur- 
rent Phenomena 

Third edition. 525 pages, 210 illustrations 4 00 

Vreeland, Frederick K.— (See Poincare, H.) 

Wait, John C— Calendar of Invention and Discovery 

Being a memorial of the personal of the greatest inventors, dis- 
coverers and scientists who have contributed to the industrial 
progress of the world. Cloth, with flap i 00 

Webb, Herbert Laws— The Telephone Handbook 

New edition. 160 pages, 133 illustrations i 00 



Wiener, A. E.— Practical Calculation of Dynamo-Electric 
Machines 

A manual for Electrical and Mechanical Engineers, and a Text- 
book for students of Electrotechnics. Second edition. 727 
pages, 381 illustrations $3 00 

Williams, Chisholm — High Frequency Currents in the 
Treatment of Disease 

222 pages, 74 illustrations 2 75 

Wright, Clarence A.— (See Freund, Leopold) 



PERIODICALS. 

Electrical World and Engineer 

An illustrated Weekly Review of Current Progress in Elec- 
tricity and its Practical Applications. Annual subscription.... 3 00 
To Foreign Countries 6 00 

General Index to the Electrical World (Subject and Author.) 

Vol. I, From January i, 1883, to January i, 1897. 372 pages. . 8 00 
Vol, II. From January i, 1897, to January i, 1903. (In prepa- 
ration.) 

American Electrician 

Monthly. Annual subscription r 00 

To Foreign Countries 2 00 

Street Railway Journal 

Weekly. Annual subscription 3 00 

To Foreign Countries 6 00 

Electric Railway Directory and Buyers' Manual 

Published three times a year. Annual subscription (Street 
Railway Journal subscribers only) I 00 

General Index to the Street Railway Journal 

By Subjects and Authors. From October, 1884, to December, 
1903, including Vols. I to XXII. Cloth, 166 large double col- 
umn pages 5 00 

The Engineering Record 

Weekly. Annual subscription 3 00 

To Foreign Countries 6 00 

Central Station List and Manual of Electric Lighting 

Quarterly. Annual subscription 4 00 

Temporary Binders 

For any of the above periodicals i 00 



ALLIS CHALMERS GO. 



a CHALMERS, GATES 1 RON 



SOLE BUILDERS OF 



Reynolds Corliss Engines 

FOR ALL POWER PURPOSES. 

RiEDLER Pumps and compressors 




This cut Is an illustration of a "REYNOLDS' ENGINE'' built for the Manhattan Railway Co., 

New York, also for the New York Rapid Transit R. R. (Tne S-abwav) There are to be eight 

of these engines in each of the power-houses. Each engine is rated at 8,000 H. P. for its most 

efficient load, and is to be capable of operating continuously under a load of 12,000 H. P. 

SPECIAL ENGINES FOR STREET RAILWAY 
AND ELECTRIC LIGHT PURPOSES 

Sederholmand Reynolds Boilers 




OENERAI^ 



OFFICE 



CHIGA60.<^ILUU.S.A. ^ 

HOME INSURANCE BUILDING. 



\LTL\hE(m. Dt 

P()KA\E. .)l2FirsU\ 



1 



New York CoivtineivtdLl 
Jewell FiltraLtioiv Co. 



NEW YORK: 
15 Broad Street. 

CHICAGO : 

40-42 W. Quincy St. 




500,000 Gallon Automatic Water Softening Plant Erected for the Columbia Chemical 
Works, Barbertou, Ohio. 

Scientific Water Softening Plants 
Filtration and Oil Extraction 

PVUE WATER. Means Greatest ECONOMY of Fuel and 
Lacbor, and Highest EFFICIENCY iiv Boiler Plant. 



GVAHANTEES m&de for RemovsLl of SCALE Matter, OIL 
a.nd SUSPENDED MATTER.. 







LEATHERIN 




A Belt i^ilter and Pre* 
seryative||%at renders 
Xreatiier B#lting imper* 
vio^s to Steam, Moist* 

lire, ffeat, Oils» Acid 
:lFu^ttt#%,: AlRalies or, 
AttnospHeric Changes, 
and forever does a\vay 
witH sticRy and gener- 
ally unsatisfactory Belt 
Dressings. 



Chas. A. Schicrcn & Co. 

Xannii«rs at^d Belt Manufactufec^S; 

NEW YORK: . 45. 47, 49, 51 Ferry Street. 



CHICAGO: 84, 86, 88 Franklin St. j PHILADELPHIA. 226 North Third St. 
BOSTON, 186-188 Lincoln St. ! PITTSBURG, 240 Thir4 Avenua. 
DENVER, 1316 Sixt*enth St. 
HAMBURG, PIckhuben 4. 







DAVIS VALVES 




In the erection of a power plant or the installation of a steam heating 
system, a question of vital importance which confronts the engineer at 
the start, and upon the wise solution of which so much depends, is the 
proper selection of steam specialties to be installed — a careful choice of such 
as will do the best work in the most satisfactory and economical manner. 
Davis Valves have been on the market for twenty-seven years, have 
successfully stood the test of time, and to-day have the enviable reputa- 
tion of being excelled by none. 



Pressure Regulators 
Pump Governors 
Back Pressure Valves 



Steam Traps 
Relief Valves 
Damper Regulators 



Balanced Valves 
Radiator Air Valves 
Stop and Check Valves 



DESCRIPTIVE CATALOUQE ON APPLICATION. 

G. M. DAVIS REGILATOR CG., 



NEW YORK: 
123 Liberty Street. 



ESTABLISHED 1876. 



CHICAGO: 
105 N. Clinton Street. 



Jeffrey. 



Coal ^ Ashes Handling 



r MACHINERY 



I For Power Plants, Etc. 1 




A Most Complete Installation including Crusher, Combined Elevator and Conveyor with 
Storage Tank Capacity— 500 Tons of Coal. 

ELEVATING— CONVEYING— POWER TRANSMISSION 

• MACHINERY 

ADDRESS 

THE JEFFREY M'F'G COMPANY, 



NEW CHAIN CATALOGUE No. 72 

NOW READY 

SEND FOR COPY 



COLUMBUS, OHIO, U. S. A. 



Berlin Construction Co., 

Designers and Manufacturers of 

STEEL BUILDINGS, BRIDGES 



and 



STRUCTURAL STEEL WORK 

of Every Description 




STEKt FRAME FOR POWER STATION OP U. O. I. CO. AT NEW ROCHELLE, N. Y. 

We make a Specialty of 

STEEL FRAME FACTORY AND SHOP CONSTRUCTION 

Designs and Estimates Furnished 

Office and Works, BERLIN, CONN. 

NEW YORK BOSTON NEWARK, N. J. 

220 BROADWAY 131 STATE STREET 142 MARKET STREET 




ESTABLISHED 1876 



INCORPORATED 1882 



WEBSTER M'F'G CO. 

ENGINEERS, FOUNDERS AND MACHINISTS 

Manufacturers of 

Power Transmitting Appliances 
Elevating and Conveying Machinery 
Gas Engines 

OFFICE AND WORKS: 1075-1097 West 15th St., CHICAGO 



Eastern Branch: 38 Dey St., New York City 



DEMING. 
TRIPLEX POWER PUMPS 

FOR OPERATION BY 

ELECTRIC MOTOR, GAS ENGINE 

OR OTHER POWER TRANSHITTED BY BELT OR DIRECT TO PUMP 

Built in many types and sizes, and adapted for Water "Wor ks> 
Boiler Feeding, Elevator Service, Mine Pumping, Etc*, Etc. 

THE ACME OF PERFECTION IN DESIGN, CONSTRUCTION AND EFFICIENCY 




Geared Pump— 4x6 




G earless Pump— 2^x3 



THE DEMING COMPANY 

Manufacturers of 

PUMPS AND HYDRAULIC MACHINERY 

SALEM, OHIO, U. S. A. 



HENION & HUBBELL, 

Chicago. 
W. P. DALLETT, 

Philadelphia. 
CHAS. J. JAGER CO., 

Boston. 
HARRIS PUMP & SUPPLY CO 

Pittsburgh. 



GENERAL AGENCIES: 

SYDNOR PUMP & WELL CO., 

Richmond. 
THE ENGLISH SUPPLY CO., 

Kansas City. 
HENDRIE & BOLTHOFF MFG. & SUPPLY CO. 

Denver. 
HENSHAW, BUCKLEY & CO., 

San Francisco. 



L. BOOTH & SONS, Los Angeles. 



UNK=BELT 
MODERN METHODS 

APPLIED TO THE HANDLING OF COAL 
AND ASHES IN A MODERN POWER PLANT. 




OUR OVERLAPPING PIVOTED BUCKET CARRIER IS SIMPLE IN CONSTRUCTION, DURABLE 
AND EFFICIENT. HANDLES BOTH COAL AND ASHES, DUMPING AT ANY DESIRED POINT. 
V^E HAVE OTHER TYPES, AND CAN FURNISH LABOR-SAVING MACHINERY TO MEET ANY 
CONDITIONS OR REQUIREMENTS. 

CATALOGS AND INFORMATION CHEERFULLY FURNISHED. 



The LINK=BELT MACHINERY COMPANY 



Philadelphia: 
Linlc-Belt En£:ineering Company. 



CHICAGO, U. S. A. 



W. W. Lindsay & Co. 



Engineers 



and 



Constructors 



for 



Steel Chimneys. 



Harrison Building 

Philadelphia, Pa. 






••••••••••••••••••^ •••••••••••••••••• 



•"FIRE FLY" 
HSBEST0S 
PHeKINGS 



The Greatest of all 



High Pressure Packings 



Used by the largest Power Plants. 

Especially adapted where super^^heat is used. 

Will outlast rubber many times, 

: 

BESTOSKINQ P. & S. COMPANY \ 

170 SUMMER STREET, BOSTON, MASS. I 

TJ. S. Agents. TURNER BROS., Ltd., RocHdale, England. ? 



>•••••••••••'••••••••••••»•-•••••••-••••<••-••••-• 



Crandall's Patent Packings 

are conceded to be the best packings 
for steam^ water^ gas or ammonia* 
Not ha\ing been subjected to the in- 
jttriotts chemical action of boiling oil, 
outlasts all others and never melt and 
gum* Ask for catalog and samples* 

"We hold the only patents on cold lubri- 
cation, and oof goods are guaranteed 
for all places where packing \s used. 

erandall Packing 60. 




Main Office and Works : 



i^alxxxyi^a, :iV« "^« 



Chicago Office: 30 La Salle St. 

Boston: Chas. A. Claflin & Co., 188 Franklin St. 



the'A B C System of Mechanical Draft 




lAfSURES 



MAXIMUM r-FFICIENCY 
INIMIM LXPENSE 



IM THE 

POWER PLANT. 



For full information secure our 
comprehensive catalogue. 



AMERICAN BLOWER COMPANY, 

DETROIT, MICH. 

NEW YORK, 141 Broadway. CHICAGO, Marquette Building. 

LONDON, 70 Gracechurch Street. 



SPECIFY 

CRANE VALVES 

AND 

CRANE FITTINGS 

for all Pressures of Steam, Gas, or Water. 



WE MAKE A SPECIALTY 

of taking contracts, from drawings for 

COMPLETE PIPING EQUIPMENTS FOR POWER PLANTS 

cut, fitted and tested, ready for erection. 

COMPLETE POCKET CATALOGUE ON REQUEST 



NEW YORK 

PHILADELPHIA 

CINCINNATI 

KANSAS CITY 

SIOUX CITY 

DULUTH 

OMAHA 



CRANE CO. 

CHrC AGO 

ESTABLISHED 1855. 



ST. PAUL 

ST. LOUIS 

SEATTLE 

MINNEAPOLIS 

LOS ANGELES 

SAN FRANCISCO 

SALT LAKE CITY 

PORTLAND, ORE. 




The 



AMER.ICAN STANDARD 



Copper Coil 
Feed Water Heater 

Before buying investigate our 

New Tube Sheet HeaLder. 



A^^-f/) 25,000 Horse Power Sold to tHe TKird 

-A.ven\ae Rail-way Co., of Ne-w YorK 
'- City, for Ilingsbrid^e Station. 

Send /or Catalogue No. 22 H. 



The WKitlock Coil Pipe Co. 



NEW YORK OFFICE, 85 Liberty Street. 



HARTFORD, CONN. 



HOLYOKE STEAM BOILER WORKS (ino 

HOLYOKE, - = - = MASS. 

We Manufacture the 

BEST TYPES OF STEAM BOILERS 

FOR 

EITHER HIGH OR LOW PRESSURE PURPOSES, 

WATER OR FIRE TUBE, 

INTERNAL OR EXTERNAL FURNACES. 

OUR WORK IS 

MORE RELIABLE AND MORE ECONOMICAL 

TMAIM AISIY OTHER. 



WE MAKE 



N/^ 



I— iirvj 



REQUIRING STEEL OR IRON IN ITS CONSTRUCTION. 



WRITE US FOR PRICES, PLANS OR ADVICE 



S^e OTIS Tubular Feed Water 
Heater and Purifier 



with Seamless Brass Tubes. 
Ovjiaranteed 

To heat the feed water to the toiling point (210 or 
212 degrees) with the exhaust steam without caus- 
ing any back pressure, also to extract the oil from 
the exhaust, so that the exhaust steam after being 
passed through the heater can be used for heating 
purposes and the water of condensation for the heat- 
ing system be returned to the boiler without the ad- 
ditional expense of an elimin<itor. 

A Liberal Offer. 

If this heater fails to give satisfaction in every re- 
spect, we pay freight, cartage, etc., both ways. 



The Stewart Heater Co., 

25 Norfolk Avenue, Buffalo. N. Y.. V. S. A. 




POWDERED COAL FUEL 



For Boilers, Annealing Ovens, Melting Furnaces, Puddling and 
Reheating Furnaces, Oxidizing and Reducing Furnaces in Chemical 
Works, Retorts, Kilns for Brick and Portland Cement Works, Etc. 

THE "CYCLONE" PULVERIZER 



THE "CYCLONE" COAL FEEDER AND BURNER 



Our system and plant is in daily operation in large and small installa- 
tions and is a commercial success. Large saving over ordinary Firing. 
Absolutely no smoke. Simple and Practical. Particulars on request. 



E. H; STROUD & CO- 
CHICAGO 



MANUFACTURERS 
30-36 LA SALLE STREET 




?"v»^"Vi?^v^'/i?^{'^t"W'/V"^r'/i?'<i?^t'^»'''t''Jw"''>i"'Vv"''<v''iC''/r^v''/^^^ 



Straight Tubes 

of seamless drawn brass expanded 
by oar special process make 

The Riblet Feed Water 
Heater and Purifier 

popular. No leaky joints, no back 
pressure, but perfect circulation and 
perfect satisfaction. Send for circular 

Erie Manufacturing and Supply Co. 

1207 Peach Street, Eric, Pa. 



ALBANY STEAM TRAPS 



We manufacture Steam Traps for 
all duties. High and Low Pressure. 



Returning- the Condensation back into Boiler or 
discharging to Hot Well, Tank or Atmosphere. 




Class C NoihRetarn Tra|>. 




Oass A. Return Trap. 

All Joints Faced and Ground. 
Removable Seats and Valves 



Class B. Non-Retam Trap 
Guaranteed for High Pressures. 



SOLD ON 30 DAYS 
TRIAL. 



SEND 



FOR CATALOGUE. No STUFFING BoxESTO Stick OR Leak. 

Albany Steam Trap Co., 



ESTABLISHED 1870. 



Albany, N. Y. 



Greater Economy, Greater Efficiency, 

BY USING 

GREEN'S Economizer 



More 
Steam 




Less 
Fuel 



CeONOMIZER tN COURSE OF ERECTION AT 8PRECKELS SUGAR REFINERY. 

NO MODERN PLANT IS COMPLETE WITHOUT IT 10 TO 20^ SAVING. 



Write for 



catalogue THE GREEN FUEL ECONOMIZER CO.. 



Matteawan, 
N. Y. 




RESULTS GUARANTEED 
ECONOMICAL IN OPERATION 

Water Softening 
Apparatus Adapted 

to each 
Peculiar Condition 

KENNICOTT WATER SOFTENER CO. 

BUTLER and 35th STS., CHICAGO 



Rubber Goods 




Behind, Hose, Packings ::^V."".t;,'","t 

For the equipmeivt of Power Plaivts, Mills, Factories, Etc. 

"'"""'""»? BOSTON BELTING CO. 



BOSTON 



NEW YORK 



ST. LOUIS 



TRADE MARK 




REGISTERED 



If you want 



tKe Best 
Get 



St^ 



N^ 



»<v< 



^^ 



tt-^ 




i^ 



60 



m 



[n ordering give exact 
diameter of Stuffing Box and 
Piston R.od or Valve Stem. 



See that our 
Jlanie and Trade Mark 
is on every package 



GOULD PACniNG CO. 

Ai.BioN Chip.man, Treas. 
EAST CAMBRIDGE:, MASS. 




TRIUMPH ELECTRIC CO. 

5?nTw°o'^'k?: CINCINNATI, OHIO, U. S. A. 



GENERATORS 

EITHER 

Direct Connected 

or 

Belted 



lK.W.to50eK.W. 




MOTORS 

AH Sizes 

AH Types 

All Applications 



lH.P.to600H.P. 



STANDARD BELTED MACHINE 



MANUFACTURERS OF HIGH GRADE 

ELECTRICAL MACHINERY 



SEND FOR CATALOGUE 



THE 



Bachman System of Water Purification 



REMOVES ALL 
SCALE FORMING 
MATTER FROM 
WATER BEFORE 
IT ENTERS THE 
BOILERS AND 
REMOVES ALL 
MUD 




RESULTS ARE 
GUARANTEED. 



NO GUESS WORK 
ABOUT OPERATION 
AND CAN BE 
RUN WITHOUT A 
CHEMIST 



D. W. & R. P. PATTERSON 



HARRISON BUILDING 



PHILADELPHIA 



STEEL CABLE ENGINEERING COMPANY 



Manufacturers of 




CONVEYING 

AND 

ELEVATING 

MACHINERY, 

COAL CRUSHERS 

SCREENS 

AND 

DRYERS for Power Plants, 
Industrial Plants, Mills, Etc. 

Main Office 
92 STATE STREET, BOSTON, MASS. 




Brandies 
NEW YORK-CHICAGO 





Jt Labor Saver 


A Fuel Economizer 


Jt Heat Producer 


Jh Money Saver 



ADAPTABLE TO ALL FORMS OF BOILER FURNACES, 
METALLURGICAL FURNACES AND TO ANY AND ALL 
PLACES WHERE UNIFORM TEMPERATURE IS DESIRED 

Practically Perfect Combvtstion and absence 
of SmoKe AvHile b\irning Bitvimino-us Coal 

Correspondence Solicited and Catalogue on A.pplication 

G^e Smokeless Stoker Company 

BOSTON, NEW YORK, CHICAGO, LONDON, E.C., BERLIN. W., 

92 State Street. 1 20 Liberty Street. Marquette Building. 37 Walbrook. Palast Hotel. 



McCORMICK TURBINES 




Represents pair 4,000 H. P. McCormick Turbines driving Generator 
and a Single Driving Exciter. Two sets built for the Hudson 
River Water Power Company, Glens Falls, New York, by 

S. MORGAN SMITH COMPANY, York, Pa., U. S. A. 



THE MEEHAN BOILER & CONSTRUCTION CO. 

LOWELLVILLE, OHIO 



STEEL PLATE CONSTRICTION 



FOR 



BLAST FURNACES 

STEEL WORKS 

ROLLING MILLS, ETC. 



Stand Pipes, Steel Riveted Pipe, Self=Supporting Steel Chimneys, 
Gas Producers, Storage Tanks, Vertical Water Tube Boilers, Etc. 



II 




rvi 



I CATALOGUE 

POWER SPECIALTY CO 126 LIBERTY ST NEW YOftK 



PE^KlilE^ 



m 



FOSTER SUPERHEATERS 

With Direct Fire or Attached to New 
or Existing Boilers. 

GREAT FUEL SAVING 
DRY STEAM ASSURED 




''l,j,'!m'n;"'%""' "'J''''' 










f^ 



COVERINGS 



SAVE 
MONEY 



\E^' 



"n lECENT tests show that more than ^ of waste by condensation in bare 
^^ I steam pipes, etc., can be SAVED by the use of proper insolation. 

"We manofactore all forms of 
ASBESTOS AND MAGNESIA SECTIONAL PIPE AND BOILER COVERINGS, 

also coverings for Hot Air, Hot and Cold Water Surfaces, and Non-Heat Conduct- 
ing Cements, all of which are made specially to prevent waste and are all money- 
savers* See paragraph, "Covering PJpes," page 95 of this book. 

A postal card request, with particulars, will bring samples with a prospectus 
of what we have to offer, or our representative will call, as you may desire. 



H. W. JOHNS-MANVILLE CO. 



MILWAUKEE 
CHICAGO 
8T. LOUIS 



JOO WILLIAM ST., NEW YORK 



PHILADELPHIA 



CLEVELAND 



PITTSBURG 
NEW ORLEANS 
LONDON 



FOR THE BEST RESULTS USE 

STEEL PIPE FLANGES 




FORGED, 

PUNCHED 

AND ROLLED 

FROM 
SOLID INGOTS 

MADE BY 

LATROBE STEEL COMPANY 



FOR HIGH 
PRESSURE 

STEAM, GAS 
AND 

WATER LINES 



MAIN OFFICE : 

1200 GIRARD BUILDING, 

PHILADELPHIA, PA. 



WORKS : 

LATROBE, 

PA. 



NEW YORK OFFICE : 

ROOM 1606.no. 11 BROADWAY, 

NEW YORK CITY. 




HaLfrisburg 
Feed Water Heaters 

Of Pure Sea.mless Copper Coils. 

Guaranteed to be the Most Effect- 
ive, Most Durable and Cheapest 
Heater Manufactured. 



Please write for descrip- 
tive catalog-. 

Copper, Iron and 
Brass Pipe Coils 
and Bends of any 
desired shape. 

CARBONIC-ACID GAS 
CYLINDERS A SPECIALTY 



MANUFACTURERS 
OF 

HIQH GRADE 

Wrought Iron 

PIPE 

BLACK 

AND 

GALVANIZED. 



MANUFACTURED BY 



The Harrisburg Pipe Jl Pipe Bending Go 

950 HERR ST.. HARRISBURG, PA. 



$i 



WEAR=WELL 



LEATHER 
PACKING 




For HYDRAULIC 
or COMPRESS 
AIR MACHINERY. 

You cannot write us 
too fully on the mat- 
ter of packings. Let 
us know what has 
been the troublewith 
the packings that you 
have been using, just 
where the weak spot 
has been; just the re- 
sults you are seeking 
Our advice is gratis. 
Send us your speci- 
fications. 




DETROIT LEATHER SPECIALTY CO. 

190 BEECHER AVENUE, DETROIT, MICHIGAN. 



The PttblicatiOfis 



of 



THe McGtaw PtfWisting Co, 



are catalogued elsewhere in tlie 
advertising pages of this book. 



should provide their plants with the most improved 
Sanitary Equipment. This would include for workmen 

THE "EM-ESS" PAR50NS CLOSET 




It is simple, easily kept 
clean, and not liable to 
get out of order. Each 
basin has an equal flush 
with a minimum amount 
of water — an important 
consideration where water 
is bought by meter. The 
flush is automatic at de- 
sired intervals. 



THE "EM-ESS" NON=SCALDING VALVE 

A valuable feature of all "Em-Ess" Shower Fix- 
tures, is a particularly desirable appliance for up-to- 
date Factories, Public Baths, Gymnasiums, Hospitals 
and all places where shower fixtures may be employed. 
It insures the bather against accidental scalding, and 
permits perfect regulation of the temperature of the 
water with this one valve. 

Two turns of the handle open the cold, and two 
more turns open the hot-water supply, allowing the 
hot and cold water to mix in the chamber of the valve. 

This mixed water may then be brought to the de 
sired temperature by opening or closing the valve, 
which decreases or increases the amount of hot or 
cold water, according to the direction in which the 
handle is turned. Two more turns close the cold 
water supply, and open the hot- water supply to its 
fullest capacity. 

Under no circumstances can the hot-water supply 
be turned on before the cold water. 
This valve, with its connections, will be furnished for Factory, Gymnasium, or Public 
Bath purposes, where it is desired to make the shower of wrought iron pipe. 

CORRESPONDENCE INVITED 

The MEYER=SNIFFEN CO., Umlted. 




SALES AND SHOWROOMS 5 EAST 19th STREET NEW YORHT 



The'' Never-SticK" 
Boiler Blo^w-Off Valve 



(PATENTED.) 



Bronze 
Cased Plug 



i:ij|||||B^H 

SECTIONAL 



Cannot 
Corrode 



We solved the problem when we devised the Locking Ring. 

Discharge Through PIu^. The Oivly Perfect Blow-Off Valve 

in the Market. 



THE "WALMANCO" JOINT. 



No 


— 1 -^ 


1 




^1 


Thread 




No 


I^^^^^^^^^B^^^vi.^P S^EB 


^B 






TIONAL V 




Hivets 


1 A\l 


J 




SEC 


EW 


1 



Tight 

First and 

Always 

Under 

250 

Pounds 



WALWORTH MANVFACTVRING CO.. 



NEW yorh office. 

ParK Row Bviilding. 



Sole M anufacturers. 



BOSTON. V. S. A. 



* 



i 



APR 13 lb'06 






^;-':* 



iSRARY OF CONGRESS 



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1;^^ 













•l^i! 






